100K Service Questions

drseth · Apr 21, 2019

Hi,

I am making up a parts list for the upcoming 100K Service and am thinking about adding an external cooler while the transmission filter/filter are changed. Assuming I might be pulling a 7000 pound travel trailer through the Rockies, what size should I get?

Here is the parts list:

DexCool 2.5 gallons
Dexron VI 9 qts, 6 for transmission, an extra if I install the cooler, 2 qts for Transfer Case
Synthetic 70W90 4 qts, 1.5 qts for front differential, and 2.1 qts for rear differential

ATF Filter Not sure if it is the short pan or tall pan
Spark Plugs Iridium (Not sure which Brand)
Spark Plug Wires????
Serpentine Belt with Pulley and Tensioner
Front Brake Pads

I have a K&N filter in the housing, but am thinking of returning to a High Capacity Paper for better filtration.

Any other suggestions as far as maintenance?

Doubeleive · Apr 21, 2019

Ya
flush all fluids: power steering, brake, coolant, transmission, transfer case, front & rear differentials.
replace all 4 02 sensors
plugs & wires
if other things have not been done consider cleaning maf, cleaning throttle body, check and clean all grounds, inspect heater hoses and fittings, inspect belts, check wheel hubs, check suspension parts, shocks, struts, ball joints, end links, sway bar bushings, motor mounts, calipers.
probably missing some things, just inspect everything 100k is a big service interval time.

drseth · Apr 21, 2019

Doubeleive said:
Ya
flush all fluids: power steering, brake, coolant, transmission, transfer case, front & rear differentials.
replace all 4 02 sensors
plugs & wires
if other things have not been done consider cleaning maf, cleaning throttle body, check and clean all grounds, inspect heater hoses and fittings, inspect belts, check wheel hubs, check suspension parts, shocks, struts, ball joints, end links, sway bar bushings, motor mounts, calipers.
probably missing some things, just inspect everything 100k is a big service interval time.

Thanks for the reply. With drive by wire, you cannot feel the stickiness of the throttle body. Had to replace a rear caliper that was sticking on a road trip from Virginia to Oregon. They did a brake flush then, along with a rear pad slap both sides. I bought front pads, so that is on the list, also.

I have a OBD2 Bluetooth dongle, and use the app Torque, which can display the O2 Sensor voltage readings, along with the catalytic converter temperature, among other things. The rear O2 Sensors usually don't need to be changed, since they basically verify the front O2 sensors and Catalytic Converter are doing their jobs, but the front ones do the real work, telling the computer the real time burn efficiency.

I haven't had a blown out water hose or heater hose since the 1980's, knock on wood.

Doubeleive · Apr 21, 2019

the 02 sensors is just my personal 02 cent's, they are rated for 100k they can last much longer of course i've just had probably more than my fair share of smog problems, sounds like you are on top of everything :cheers:

drseth · Apr 22, 2019

I am at the auto parts store picking up things. Valvoline has this 75W-140 with limited slip additive, and had a GM 9985991 rating. Would I need additive if I buy the synthetic 75W-90?

Is this a big deal?

Derick · Apr 22, 2019

Spec calls for 75W-90. Valvoline has a LS gear oil ready to use in 75W-90. Check your production codes to ensure you have a LS diff.

https://www.autozone.com/greases-an...ynthetic-gear-oil-sae-75w-90-32-oz/977482_0_0

Just used that in my diff service I did recently.

That said, I asked once about using 75W-140, and it wasnt necessary. I put the heavier oil in my sequoia, and never had a problem. You might lose 1 or 2 MPG.

drseth · Apr 22, 2019

Derick said:
Spec calls for 75W-90. Valvoline has a LS gear oil ready to use in 75W-90. Check your production codes to ensure you have a LS diff.

https://www.autozone.com/greases-an...ynthetic-gear-oil-sae-75w-90-32-oz/977482_0_0

Just used that in my diff service I did recently.

That said, I asked once about using 75W-140, and it wasnt necessary. I put the heavier oil in my sequoia, and never had a problem. You might lose 1 or 2 MPG.

drseth · Apr 22, 2019

My rig has a limited slip rear, so I want additive .Guess I will find the 75W 90 with LS additive.

I have not had any problems despite extended change intervals using Mobile 1 or QS UD, along with a Purolator filter

Power steering fluid change? How much to do the job?

intheburbs · Apr 23, 2019

GM recommends 80W90 for your front axle, and 75W90 for the rear. Just sayin'. And it's not a limited-slip. It's a locker.

Personally, I'm not a fan of iridium. They didn't seem to last as long as the OEM platinum plugs.

I actually take my truck to the dealership and have them do a full flush on the trans - 16 quarts. Costs like $230. Just did my Denali, as it rolled over 100k last month, will be doing the Burb this summer as it's approaching 200k.

I tow an 8600-lb trailer through the Rockies, including a run through the Eisenhower Tunnel. Never saw the need for an additional/bigger trans cooler.

Make sure you hit all the grease zerks in the suspension; pay extra attention to your ball joints.

How are your shocks/struts? Even though I wasn't feeling anything per se, I did the shocks/struts on the Denali, figuring 100k was about their usable lifespan.

Doubeleive · Apr 23, 2019

drseth said:
My rig has a limited slip rear, so I want additive .Guess I will find the 75W 90 with LS additive.

I have not had any problems despite extended change intervals using Mobile 1 or QS UD, along with a Purolator filter

Power steering fluid change? How much to do the job?

if you are flushing the power steering it takes about a gallon to get it back to clear looking again

100K Service Questions

drseth

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Doubeleive

Wes

drseth

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Doubeleive

Wes

drseth

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Derick

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drseth

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drseth

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intheburbs

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Doubeleive

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