chauncey0337
Full Access Member
Add limited slip additive or not? 2000 5.3l Rear diff code G80. Just serviced mine. I've heard mixed opinions but not a whole lot of facts. Fill me in.
Limited slip additive or not?
- Thread starter chauncey0337
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HiHoeSilver
Away!
Lots of blurry opinions on this one, for sure. What oil are you using?
OP
OP
chauncey0337
Full Access Member
Lucas synthetic 75w-90 gear oil.
Chubbs
Full Access Member
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NO additives! Pickup trucks and SUVs equipped with g80 do not require the additive. Only limited-slip diff in select performance cars and vehicles of that nature will call for that particular chemical additive or fluid spec. Your owner manual or service guidelines will state synthetic gear lube ONLY, for the rear axle.
Fluid and Lubricant Recommendations
Fluid and Lubricant Recommendations
Fluid and Lubricant Recommendations
Usage Fluid/Lubricant
Engine Oil
Engine oil with the American Petroleum Institute Certified For Gasoline Engines STARBURST symbol of the proper viscosity. To determine the preferred viscosity for this vehicle's engine, refer to Explanation of Scheduled Maintenance.
Engine Coolant
50/50 mixture of clean drinkable water and use only GM Goodwrench® DEX-COOL® or Havoline® DEX-COOL® coolant.
Hydraulic Brake System
Delco Supreme 11® Brake Fluid (GM P/N 12377967 or equivalent DOT-3 brake fluid).
Parking Brake Cable Guides
Chassis lubricant (GM P/N 12377985 or equivalent) meeting requirements of NLGI Grade 2, Category GC or GC-LB
Power Steering System
GM Hydraulic Power Steering Fluid (GM P/N 1052884 - 1 pint, 1050017 - 1 quart, or equivalent).
Automatic Transmission
DEXRON®-III Automatic Transmission Fluid
Key Lock Cylinders
Multi-Purpose Lubricant, Superlube® (GM P/N 12346241 or equivalent).
Chassis Lubrication
Chassis lubricant (GM P/N 12377985 or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category GC or GC-LB.
Rear Wheel Bearings
Wheel bearing lubricant (GM P/N 1051344) or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category GC or GC-LB
Front Axle (S4WD)
SAE 80W-90 Axle Lubricant (GM P/N 89021671, Canadian P/N 10950849 or equivalent).
Front Axle (F4WD and all 9.25)
SAE 75W-90 Synthetic Axle Lubricant (GM P/N 12378261, Canadian P/N 10953455) or equivalent meeting GM Specification 9986115.
Rear Axle
Axle Lubricant (GM P/N 12378261) SAE 75W-90 Synthetic or equivalent meeting GM Specification 9986115.
Transfer Case
Manual Transmission Fluid GM P/N 88861800 (Canadian P/N 88861801)
Automatic Transfer Case
Automatic transfer case fluid (GM P/N 12378396)
Windshield Washer Solvent
GM Optikleen® Washer Solvent (GM P/N 1051515) or equivalent
Hood Latch Assembly
Lubriplate lubricant aerosol (GM P/N 12346293 or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category LB or GC-LB.
Hood and Door Hinges
Multi-Purpose lubricant, Superlube® (GM P/N 12346241 or equivalent).
Weatherstrip Conditioning
Dielectric Silicone Grease (GM P/N 12345579 or equivalent).
Fluid and Lubricant Recommendations
Fluid and Lubricant Recommendations
Usage Fluid/Lubricant
Engine Oil (Gasoline Engine)
Engine Oil with the American Petroleum Institute Certified for Gasoline Engines Starburst symbol of the proper viscosity. To determine the preferred viscosity for your vehicle's engine, refer to Engine Oil Viscosity in Explanation of Scheduled Services.
Engine Oil (Diesel Engine)
Engine Oil with the letters CG-4 designation may appear either alone, or in combination with other API designations, such as API CG-4/SH, CG-4/SJ, SH/CG-4, or SJ/CG-4. These letters show American Petroleum Institute (API) levels of quality. To determine the preferred viscosity for your vehicle's diesel engine.
Engine Coolant
50/50 mixture of clean, drinkable water and use only GM Goodwrench® DEX-COOL® or Havoline® DEX-COOL® Coolant.
Hydraulic Brake System
Delco Supreme 11® Brake Fluid (GM P/N 12377967 or equivalent DOT-3 Brake Fluid).
Windshield Washer Solvent
GM Optikleen® Washer Solvent (GM P/N 1051515) or equivalent.
Hydraulic Clutch System
Hydraulic Clutch Fluid (GM P/N 12345347 or equivalent DOT-3 Brake Fluid).
Parking Brake Cable Guides
Chassis Lubricant (GM P/N 12377985 or equivalent meeting requirements of NLGI#2, Category LB or GC-LB.
Power Steering System
GM Power Steering Fluid (GM P/N 1052884 - 0.4732 liters (1 pint), 1050017 - 0.9464 liters (1 quart), or equivalent).
Manual Transmission (5-Speed with Low Gear, RPO MW3)
GM Goodwrench Synthetic Manual Transmission Fluid (GM P/N 12346190 - 0.9464 liters (1 quart) or equivalent SAE 75W-90 GL-4 Gear Oil.
Automatic Transmission
DEXRON®-III Automatic Transmission Fluid
Key Lock Cylinders
Multi-Purpose Lubricant, Superlube® (GM P/N 12346241 or equivalent).
Floor Shift Linkage
Lubriplate® Lubricant Aerosol (GM P/N 12346293 or equivalent) or lubricant meeting requirements of NLGI #2, Category LB or GC-LB.
Chassis Lubrication
Chassis Lubricant (GM P/N 12377985 or equivalent) or Lubricant meeting requirements of NLGI No. 2, Category LB or GC-LB.
Front Wheel Bearings (RWD)
Wheel Bearing Lubricant meeting requirements of NLGI #2, Category GC or GC-LB (GM P/N 105344 or equivalent).
Front Axle (S4WD)
SAE 80W-90 Axle Lubricant (GM P/N 89021671, Canadian P/N 10950849 or equivalent).
Front Axle (F4WD and all 9.25)
SAE 75W-90 Synthetic Axle Lubricant (GM P/N 12378261, Canadian P/N 10953455) or equivalent meeting GM Specification 9986115.
Rear Axle
SAE 75W-90 Synthetic Axle Lubricant, GM P/N 12378261 (Canadian P/N 10953455) or equivalent meeting GM Specification 9986115.
Differential, C3 (HD3500) Trucks With Dana Rear Axle
SAE 75W-140 Synthetic Axle Lubricant (GM P/N 12346140) or equivalent.
Manual Transfer Case
DEXRON®-III Automatic Transmission Fluid.
Automatic Transfer Case
Automatic Transfer Case Fluid (GM P/N 12378396).
Front Axle Propshaft Spline, Rear Driveline Center Splines and Universal Joints
Chassis Lubricant (GM P/N 12377985 or equivalent) or lubricant meeting requirements of NLGI #2, Category LB or GC-LB.
One-Piece Propshaft Spline (Two-Wheel Drive with Auto. Trans)
Spline Lubricant, Special Lubricant (GM P/N 12345879) or lubricant meeting requirements of GM 9985830.
Hood Latch Assembly, Secondary Latch, Pivots, Spring Anchor and Release Pawl.
Lubriplate® Lubricant Aerosol (GM P/N 12346293 or equivalent) or lubricant meeting requirements of NLGI #2, Category LB or GC-LB.
Hood and Door Hinges
Multi-Purpose Lubricant, Superlube® (GM P/N 12346241 or equivalent).
Body Door Hinge Pins, Tailgate Hinge and Linkage Folding Seat and Fuel Door Hinge
Multi-Purpose Lubricant Superlube® (GM P/N 12346241 or equivalent).
Tailgate Handle Pivot Points, Hinges, Latch Bolt and Linkage
Multi-Purpose Lubricant Superlube® (GM P/N 12346241 or equivalent).
Weatherstrip Conditioning
Dielectric Silicone Grease (GM P/N 12346241 or equivalent).
Weatherstrip Squeaks
Synthetic Grease with teflon, Superlube® (GM P/N 12371287 or equivalent).
Some manufacturers will add a small amount of friction modifiers to their gear oil, and this is where people get confused. The Mobil-1 gear lube with additive will not envoke any ill effects for a differential that does not require it, supposedly. I don't use it but I've read where a lot of Tahoe owners do. I think Mobil is over rated so I just assume buy a brand that doesn't have any friction modifier but it's whatever.
Fluid and Lubricant Recommendations
Fluid and Lubricant Recommendations
Fluid and Lubricant Recommendations
Usage Fluid/Lubricant
Engine Oil
Engine oil with the American Petroleum Institute Certified For Gasoline Engines STARBURST symbol of the proper viscosity. To determine the preferred viscosity for this vehicle's engine, refer to Explanation of Scheduled Maintenance.
Engine Coolant
50/50 mixture of clean drinkable water and use only GM Goodwrench® DEX-COOL® or Havoline® DEX-COOL® coolant.
Hydraulic Brake System
Delco Supreme 11® Brake Fluid (GM P/N 12377967 or equivalent DOT-3 brake fluid).
Parking Brake Cable Guides
Chassis lubricant (GM P/N 12377985 or equivalent) meeting requirements of NLGI Grade 2, Category GC or GC-LB
Power Steering System
GM Hydraulic Power Steering Fluid (GM P/N 1052884 - 1 pint, 1050017 - 1 quart, or equivalent).
Automatic Transmission
DEXRON®-III Automatic Transmission Fluid
Key Lock Cylinders
Multi-Purpose Lubricant, Superlube® (GM P/N 12346241 or equivalent).
Chassis Lubrication
Chassis lubricant (GM P/N 12377985 or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category GC or GC-LB.
Rear Wheel Bearings
Wheel bearing lubricant (GM P/N 1051344) or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category GC or GC-LB
Front Axle (S4WD)
SAE 80W-90 Axle Lubricant (GM P/N 89021671, Canadian P/N 10950849 or equivalent).
Front Axle (F4WD and all 9.25)
SAE 75W-90 Synthetic Axle Lubricant (GM P/N 12378261, Canadian P/N 10953455) or equivalent meeting GM Specification 9986115.
Rear Axle
Axle Lubricant (GM P/N 12378261) SAE 75W-90 Synthetic or equivalent meeting GM Specification 9986115.
Transfer Case
Manual Transmission Fluid GM P/N 88861800 (Canadian P/N 88861801)
Automatic Transfer Case
Automatic transfer case fluid (GM P/N 12378396)
Windshield Washer Solvent
GM Optikleen® Washer Solvent (GM P/N 1051515) or equivalent
Hood Latch Assembly
- Pivots and Spring Anchor
- Release Pawl
Lubriplate lubricant aerosol (GM P/N 12346293 or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category LB or GC-LB.
Hood and Door Hinges
Multi-Purpose lubricant, Superlube® (GM P/N 12346241 or equivalent).
Weatherstrip Conditioning
Dielectric Silicone Grease (GM P/N 12345579 or equivalent).
Fluid and Lubricant Recommendations
Fluid and Lubricant Recommendations
Usage Fluid/Lubricant
Engine Oil (Gasoline Engine)
Engine Oil with the American Petroleum Institute Certified for Gasoline Engines Starburst symbol of the proper viscosity. To determine the preferred viscosity for your vehicle's engine, refer to Engine Oil Viscosity in Explanation of Scheduled Services.
Engine Oil (Diesel Engine)
Engine Oil with the letters CG-4 designation may appear either alone, or in combination with other API designations, such as API CG-4/SH, CG-4/SJ, SH/CG-4, or SJ/CG-4. These letters show American Petroleum Institute (API) levels of quality. To determine the preferred viscosity for your vehicle's diesel engine.
Engine Coolant
50/50 mixture of clean, drinkable water and use only GM Goodwrench® DEX-COOL® or Havoline® DEX-COOL® Coolant.
Hydraulic Brake System
Delco Supreme 11® Brake Fluid (GM P/N 12377967 or equivalent DOT-3 Brake Fluid).
Windshield Washer Solvent
GM Optikleen® Washer Solvent (GM P/N 1051515) or equivalent.
Hydraulic Clutch System
Hydraulic Clutch Fluid (GM P/N 12345347 or equivalent DOT-3 Brake Fluid).
Parking Brake Cable Guides
Chassis Lubricant (GM P/N 12377985 or equivalent meeting requirements of NLGI#2, Category LB or GC-LB.
Power Steering System
GM Power Steering Fluid (GM P/N 1052884 - 0.4732 liters (1 pint), 1050017 - 0.9464 liters (1 quart), or equivalent).
Manual Transmission (5-Speed with Low Gear, RPO MW3)
GM Goodwrench Synthetic Manual Transmission Fluid (GM P/N 12346190 - 0.9464 liters (1 quart) or equivalent SAE 75W-90 GL-4 Gear Oil.
Automatic Transmission
DEXRON®-III Automatic Transmission Fluid
Key Lock Cylinders
Multi-Purpose Lubricant, Superlube® (GM P/N 12346241 or equivalent).
Floor Shift Linkage
Lubriplate® Lubricant Aerosol (GM P/N 12346293 or equivalent) or lubricant meeting requirements of NLGI #2, Category LB or GC-LB.
Chassis Lubrication
Chassis Lubricant (GM P/N 12377985 or equivalent) or Lubricant meeting requirements of NLGI No. 2, Category LB or GC-LB.
Front Wheel Bearings (RWD)
Wheel Bearing Lubricant meeting requirements of NLGI #2, Category GC or GC-LB (GM P/N 105344 or equivalent).
Front Axle (S4WD)
SAE 80W-90 Axle Lubricant (GM P/N 89021671, Canadian P/N 10950849 or equivalent).
Front Axle (F4WD and all 9.25)
SAE 75W-90 Synthetic Axle Lubricant (GM P/N 12378261, Canadian P/N 10953455) or equivalent meeting GM Specification 9986115.
Rear Axle
SAE 75W-90 Synthetic Axle Lubricant, GM P/N 12378261 (Canadian P/N 10953455) or equivalent meeting GM Specification 9986115.
Differential, C3 (HD3500) Trucks With Dana Rear Axle
SAE 75W-140 Synthetic Axle Lubricant (GM P/N 12346140) or equivalent.
Manual Transfer Case
DEXRON®-III Automatic Transmission Fluid.
Automatic Transfer Case
Automatic Transfer Case Fluid (GM P/N 12378396).
Front Axle Propshaft Spline, Rear Driveline Center Splines and Universal Joints
Chassis Lubricant (GM P/N 12377985 or equivalent) or lubricant meeting requirements of NLGI #2, Category LB or GC-LB.
One-Piece Propshaft Spline (Two-Wheel Drive with Auto. Trans)
Spline Lubricant, Special Lubricant (GM P/N 12345879) or lubricant meeting requirements of GM 9985830.
Hood Latch Assembly, Secondary Latch, Pivots, Spring Anchor and Release Pawl.
Lubriplate® Lubricant Aerosol (GM P/N 12346293 or equivalent) or lubricant meeting requirements of NLGI #2, Category LB or GC-LB.
Hood and Door Hinges
Multi-Purpose Lubricant, Superlube® (GM P/N 12346241 or equivalent).
Body Door Hinge Pins, Tailgate Hinge and Linkage Folding Seat and Fuel Door Hinge
Multi-Purpose Lubricant Superlube® (GM P/N 12346241 or equivalent).
Tailgate Handle Pivot Points, Hinges, Latch Bolt and Linkage
Multi-Purpose Lubricant Superlube® (GM P/N 12346241 or equivalent).
Weatherstrip Conditioning
Dielectric Silicone Grease (GM P/N 12346241 or equivalent).
Weatherstrip Squeaks
Synthetic Grease with teflon, Superlube® (GM P/N 12371287 or equivalent).
Some manufacturers will add a small amount of friction modifiers to their gear oil, and this is where people get confused. The Mobil-1 gear lube with additive will not envoke any ill effects for a differential that does not require it, supposedly. I don't use it but I've read where a lot of Tahoe owners do. I think Mobil is over rated so I just assume buy a brand that doesn't have any friction modifier but it's whatever.
Last edited:
I would play it by ear, if you can hear it grinding/binding up then add the additive, if not then don't worry about it, I had to add it sometimes and sometimes not (I have been thru a few rear ends)
swathdiver
Full Access Member
There is no controversy if you read the manual. The original part number in your manual is 12378261 and this has been superseded by 88900401 or AC Delco 10-4016.
This fluid contains the limited slip additive as does the Mobil One synthetic gear oil.
HiHoeSilver
Away!
This is why I asked about which oil. The royal purple has it too.
915_Tahoe
Your GM Parts Specialist
GM# 88900330
ACDELCO# 10-4003
THIS MUST BE ADDED WHEN SERVICING YOUR REAR DIFF, IF YOU HAVE LIMITED SLIP.
ACDELCO# 10-4003
THIS MUST BE ADDED WHEN SERVICING YOUR REAR DIFF, IF YOU HAVE LIMITED SLIP.
Chubbs
Full Access Member
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- Jun 24, 2017
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Soooo much contradictory information being thrown around in this thread.
Once again, for full size SUV & pickup trucks, no modifiers should be used or added.
STRICTLY gear oil, nothing more & nothing less
"Originally Posted by General Motors
LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849).
The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.
VEHICLES/COMPONENTS INVOLVED: ----------------------------- Some light duty trucks equipped with locking rear axles, RPO G80.
SERVICE PARTS INFORMATION:
Part Number Description ----------- ------------------ 10950849 Lubricant, Rear Axle (1 litre)
Parts are currently available through CANSPO.
WARRANTY INFORMATION:
As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
© Copyright General Motors Corporation. All Rights Reserved."
I apologize for all of the confusing info being posted here. Our more active members that have posted here on this subject are far off the mark this time.
@915_Tahoe
That lube has no business being associated with a Tahoe in any way. These trucks do not have a limited slip type diff.
Once again, for full size SUV & pickup trucks, no modifiers should be used or added.
STRICTLY gear oil, nothing more & nothing less
"Originally Posted by General Motors
LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849).
The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.
VEHICLES/COMPONENTS INVOLVED: ----------------------------- Some light duty trucks equipped with locking rear axles, RPO G80.
SERVICE PARTS INFORMATION:
Part Number Description ----------- ------------------ 10950849 Lubricant, Rear Axle (1 litre)
Parts are currently available through CANSPO.
WARRANTY INFORMATION:
As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
© Copyright General Motors Corporation. All Rights Reserved."
I apologize for all of the confusing info being posted here. Our more active members that have posted here on this subject are far off the mark this time.
@915_Tahoe
That lube has no business being associated with a Tahoe in any way. These trucks do not have a limited slip type diff.
Chubbs
Full Access Member
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Because you are adding chems not meant to be used in a g80??
Don't even mention limited slip, doesn't apply except towards creating more confusion, which is why the OP started the thread in the 1st place.
This post should be removed from the thread, entirely
NO because I used to drive like a crazed maniac 24/7 and broke stuff a lot, if it makes noise/binds then the additive resolves that issue, not everyone has a g80 or even uses one, the g80 is weak in my book anyway upgrade to a Detroit cost's more but wont break.
swathdiver
Full Access Member
afpj
Full Access Member
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I believe he's saying that the g80 locking rear differential is NOT a limited slip differential, so the latter term should not be used when referring to the G80.
swathdiver
Full Access Member
If so, he would be mistaken. The GMT800 and the GMT900 and the K2XX all have a differential with a limited slip function and a locking function. Details have been posted on this forum before and it can be read about in the GM Restoration files for each truck and in the shop manuals.
HiHoeSilver
Away!
afpj
Full Access Member
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So the g80 is considered a limited slip differential that has a locking function?
swathdiver
Full Access Member
Yessir. The G80 in my old 1980s Buick was a limited slip. I can see literature where the locking feature was added to trucks in the 1980s but have not looked into the history of that. So even the GMT400s could have it but I do not know as I have not looked.
Anyhow, here's a quick explanation on what it look likes and how it works:
HiHoeSilver
Away!
Yes. The GMT400 had it.
afpj
Full Access Member
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Man I love this site. Learn something new every time. I just hope my yuk lasts long enough for me to put that learning to use. (185k with pretty prominent piston slap, or is it rod knock?) 
Trailblazzin
Full Access Member
Watched the video and looked like just a regular locking rear carrier, nothing limited slip about it.
Either locked or open.......
Sent from my iPhone using Tapatalk
Either locked or open.......
Sent from my iPhone using Tapatalk
