2008 5.3 Engine Oil/Filter + Octane Rating

CruelJung · Jul 25, 2022

I drive a 2008 Yukon XL, 5.3 1500 Flex Fuel. The vehicle has 170,000+ miles on it and the AFM/DOD is both mechanically and electronically deleted. I am interested in doing my own oil changes and would like to know what oil and filter brands are most ideal for engine health and longevity.

From my current base of knowledge, I am leaning towards a Wix filter and Amsoil synthetic oil (my vehicle has already been running on synthetic, with AC Delco filters). Any suggestions or experience?

Additionally, is there any reason to run my vehicle on higher octane fuel than 87 unleaded?

iamdub · Jul 25, 2022

LandYachtFL said:
I drive a 2008 Yukon XL, 5.3 1500 Flex Fuel. The vehicle has 170,000+ miles on it and the AFM/DOD is both mechanically and electronically deleted. I am interested in doing my own oil changes and would like to know what oil and filter brands are most ideal for engine health and longevity.

From my current base of knowledge, I am leaning towards a Wix filter and Amsoil synthetic oil (my vehicle has already been running on synthetic, with AC Delco filters). Any suggestions or experience?

Additionally, is there any reason to run my vehicle on higher octane fuel than 87 unleaded?

Good job on already running synthetic. Wix is a great filter. You're all set there.

When mine was 100% stock, it would have spark knock if I gave it some moderate throttle to accelerate during hot weather if I ran 87. I know it'd knock a lot more if I were towing. 89 made a considerable improvement- it'd only knock if I floored it from a stop and only for a few ticks. 91-93 eliminated the knock. I can't say mine represents the masses. So, just listen to yours. If it knocks (sounds like clicks under load), run 89 or higher. This might only be necessary during the summer and/or if you have a little fun when you drive.

Speaking of oil, are you aware of any oil consumption? Do you check the level regularly? The PCV system in the earlier Gen 4 engines contributed to oil consumption. One of the functions of AFM exacerbated the issue. It was [mostly] resolved with a revised PCV baffle design in the driver side valve cover around 2010. If yours still has the original cover, I'd recommend you get the updated one. Also, I highly recommend a catch can.

CruelJung · Aug 1, 2022

iamdub said:
Good job on already running synthetic. Wix is a great filter. You're all set there.

When mine was 100% stock, it would have spark knock if I gave it some moderate throttle to accelerate during hot weather if I ran 87. I know it'd knock a lot more if I were towing. 89 made a considerable improvement- it'd only knock if I floored it from a stop and only for a few ticks. 91-93 eliminated the knock. I can't say mine represents the masses. So, just listen to yours. If it knocks (sounds like clicks under load), run 89 or higher. This might only be necessary during the summer and/or if you have a little fun when you drive.

Speaking of oil, are you aware of any oil consumption? Do you check the level regularly? The PCV system in the earlier Gen 4 engines contributed to oil consumption. One of the functions of AFM exacerbated the issue. It was [mostly] resolved with a revised PCV baffle design in the driver side valve cover around 2010. If yours still has the original cover, I'd recommend you get the updated one. Also, I highly recommend a catch can.

Thank you for the response. I did change the oil myself, so the engine is now running with Amsoil Signature and an Amsoil EAO17 filter. I can't say if I've heard any knocking in the engine when accelerating or otherwise, but that's something I will pay closer attention to moving forward. I see on your signature that you have also deleted your truck's AFM; in reference to the knock you were experiencing prior to the delete, what octane do you run your Tahoe on now?

I will have to look into PCV system on my vehicle. I had quite a bit of work done on the engine as part of the AFM delete. I don't know about oil consumption, but I do have a minor leak around the bell housing. It was noticed when my oil was changed previously and is still active, but minor.

Before deciding to change my oil myself, after making a 6hr round trip, I noticed my oil filter was leaking and the day after returning I checked the oil before driving--it was very low. Needless to say, it seemed the right time to start doing my own oil changes. 4-5 quarts is about what I drained, but I can't say yet if that was due to the filter leaking or oil consumption. It's something I will be paying close attention to now.

donjetman · Aug 1, 2022

Valve cover driverside – GM# 12570427 - amazon etc

Catch can - https://www.amazon.com/PQY-Catch-Ba...9385144&sprefix=catch+can,aps,129&sr=8-8&th=1

iamdub · Aug 2, 2022

LandYachtFL said:
Thank you for the response. I did change the oil myself, so the engine is now running with Amsoil Signature and an Amsoil EAO17 filter. I can't say if I've heard any knocking in the engine when accelerating or otherwise, but that's something I will pay closer attention to moving forward. I see on your signature that you have also deleted your truck's AFM; in reference to the knock you were experiencing prior to the delete, what octane do you run your Tahoe on now?

I run 93 now just as I did before. But, I HAVE to now. That simple delete turned into a small performance upgrade- cam, stall, higher compression, tuned for 93, etc. I just think these things, in purely stock form, benefit from at least 89 and rely on the knock sensors to retard the timing, making 87 "acceptable" and that's what GM specs in the manual. I don't want any knock. Even if I had stuck to my "stock" AFM delete, I would still run 93. A few extra bucks per fill-up is still way cheaper than fractured pistons and/or rings. I'd rather the peace of mind when flooring it to pass during hot weather or when towing.

Coincidentally, I recently ran the tank very low and added about 15 gallons of 89 as a test to see "how close to the ragged edge" the tuning was. Let's just say I'm driving it easy and bought a can of octane booster until I'm due to refuel.

LandYachtFL said:
I will have to look into PCV system on my vehicle. I had quite a bit of work done on the engine as part of the AFM delete. I don't know about oil consumption, but I do have a minor leak around the bell housing. It was noticed when my oil was changed previously and is still active, but minor.

Before deciding to change my oil myself, after making a 6hr round trip, I noticed my oil filter was leaking and the day after returning I checked the oil before driving--it was very low. Needless to say, it seemed the right time to start doing my own oil changes. 4-5 quarts is about what I drained, but I can't say yet if that was due to the filter leaking or oil consumption. It's something I will be paying close attention to now.

Good call. Keep an eye on it and know your machine. It'd be reassuring to at least know if that driver side valve cover (as @donjetman graciously linked) was updated during your engine work. The catch can he also linked is fine. My only suggestion is to add a stainless scrubber pad for more filtering media. It goes on top of that round plate with the holes in it.

https://www.amazon.com/Scotch-Brite-214C-Stainless-Scrubbing-Scouring/dp/B002CQTXBC/ref=asc_df_B002CQTXBC/?tag=hyprod-20&linkCode=df0&hvadid=198085753806&hvpos=&hvnetw=g&hvrand=2580842754734806056&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9025338&hvtargid=pla-351298315324&psc=1

CruelJung · Aug 8, 2022

iamdub said:
I run 93 now just as I did before. But, I HAVE to now. That simple delete turned into a small performance upgrade- cam, stall, higher compression, tuned for 93, etc. I just think these things, in purely stock form, benefit from at least 89 and rely on the knock sensors to retard the timing, making 87 "acceptable" and that's what GM specs in the manual. I don't want any knock. Even if I had stuck to my "stock" AFM delete, I would still run 93. A few extra bucks per fill-up is still way cheaper than fractured pistons and/or rings. I'd rather the peace of mind when flooring it to pass during hot weather or when towing.

Coincidentally, I recently ran the tank very low and added about 15 gallons of 89 as a test to see "how close to the ragged edge" the tuning was. Let's just say I'm driving it easy and bought a can of octane booster until I'm due to refuel.

Good call. Keep an eye on it and know your machine. It'd be reassuring to at least know if that driver side valve cover (as @donjetman graciously linked) was updated during your engine work. The catch can he also linked is fine. My only suggestion is to add a stainless scrubber pad for more filtering media. It goes on top of that round plate with the holes in it.

https://www.amazon.com/Scotch-Brite-214C-Stainless-Scrubbing-Scouring/dp/B002CQTXBC/ref=asc_df_B002CQTXBC/?tag=hyprod-20&linkCode=df0&hvadid=198085753806&hvpos=&hvnetw=g&hvrand=2580842754734806056&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9025338&hvtargid=pla-351298315324&psc=1

I just filled up with 93 to see if the engine ran differently and, while it could just be a placebo effect, the engine seems to run a bit more smoothly than before.

On the note of 'knock,' I have had a rumble/rattle sound since I acquired the vehicle that seemed to occur on regular, looped intervals while in drive or idle--with a corresponding vibration on the gas pedal. My mechanic thought it was coming from the catalytic converter(s), but I don't have any OBDII codes showing for that. The only codes my PCM gives me are P1153 and P1133, and I've already replaced my two upstream O2 sensors as a response--still get the codes, though. The Diablo Predator II I deleted the AFM with comes in handy to read/delete these codes, but it's something I would like to figure out over time. I only mention this because I figure my fuel injectors and these other factors you've mentioned could be related to these codes and that the vibration/sound *could* be knock.

At any rate, I plan to start using another Amsoil product, Pi, every so often alongside higher octane fuel (I'll try 91 next time and compare)--as well as a catch can and/or other upgrades--to clean up anything possible and ensure the engine is being cared for.

I greatly appreciate the detailed responses; it's been very helpful.

iamdub · Aug 10, 2022

LandYachtFL said:
I just filled up with 93 to see if the engine ran differently and, while it could just be a placebo effect, the engine seems to run a bit more smoothly than before.

On the note of 'knock,' I have had a rumble/rattle sound since I acquired the vehicle that seemed to occur on regular, looped intervals while in drive or idle--with a corresponding vibration on the gas pedal. My mechanic thought it was coming from the catalytic converter(s), but I don't have any OBDII codes showing for that. The only codes my PCM gives me are P1153 and P1133, and I've already replaced my two upstream O2 sensors as a response--still get the codes, though. The Diablo Predator II I deleted the AFM with comes in handy to read/delete these codes, but it's something I would like to figure out over time. I only mention this because I figure my fuel injectors and these other factors you've mentioned could be related to these codes and that the vibration/sound *could* be knock.

At any rate, I plan to start using another Amsoil product, Pi, every so often alongside higher octane fuel (I'll try 91 next time and compare)--as well as a catch can and/or other upgrades--to clean up anything possible and ensure the engine is being cared for.

I greatly appreciate the detailed responses; it's been very helpful.

Pinging/spark knock isn't gonna happen at idle or while sitting in gear. If it happens, it should only be when the engine's under a decent amount of load, like with hard throttle and accelerating while towing, or just really hard throttle, WOT when passing, etc. It'll only do it a few times and stop since the PCM will retard the timing. Basically, you punch it from a stop and it'll click a few times then not click any more. You won't necessarily feel the reduction in power.

CruelJung · Sep 26, 2022

iamdub said:
Pinging/spark knock isn't gonna happen at idle or while sitting in gear. If it happens, it should only be when the engine's under a decent amount of load, like with hard throttle and accelerating while towing, or just really hard throttle, WOT when passing, etc. It'll only do it a few times and stop since the PCM will retard the timing. Basically, you punch it from a stop and it'll click a few times then not click any more. You won't necessarily feel the reduction in power.

Based upon that description, I don't think my engine is experiencing any spark knock with any of the octane ratings I've tried now (87, 89, 91, and 93). In fact, I recently added a fuel system cleaner (Amsoil PI) when filling my tank and that recurrent noise I described earlier seems to have ceased--which is great. If my experience with the fuel additive continues positively I'll repeat its use every oil change (3-4k miles).

My PCM is tuned for 87 (performance) at the moment. I would like to try the "Diablo Tune" (93) at some point, but not before I work on a few more things to shore up my confidence in the engine's capacity for the advanced timing.

Up next: PCV and oil leak investigation, then likely a catch can followed by an intake upgrade--I like the Airaid MIT/AEM dryflow filter combination, but would like to know more about it.

I appreciate everyone and their input in this thread, but I have to give a special thanks to you for all the details and thoughtful responses; I've checked out your build documentation, too, which is a gift to say the least. It's dubious if I will ever undergo a process like yours with my Yukon, but who knows?

swathdiver · Sep 26, 2022

CruelJung said:
Based upon that description, I don't think my engine is experiencing any spark knock with any of the octane ratings I've tried now (87, 89, 91, and 93). In fact, I recently added a fuel system cleaner (Amsoil PI) when filling my tank and that recurrent noise I described earlier seems to have ceased--which is great. If my experience with the fuel additive continues positively I'll repeat its use every oil change (3-4k miles).

My PCM is tuned for 87 (performance) at the moment. I would like to try the "Diablo Tune" (93) at some point, but not before I work on a few more things to shore up my confidence in the engine's capacity for the advanced timing.

Up next: PCV and oil leak investigation, then likely a catch can followed by an intake upgrade--I like the Airaid MIT/AEM dryflow filter combination, but would like to know more about it.

I appreciate everyone and their input in this thread, but I have to give a special thanks to you for all the details and thoughtful responses; I've checked out your build documentation, too, which is a gift to say the least. It's dubious if I will ever undergo a process like yours with my Yukon, but who knows?

You will be hard pressed to hear the motor knocking, we're just too insulated. You can see it on a scan tool though.

Excepting DI engines, all engines benefit from running higher octane fuel, smoother idle, better mileage, burned cleaner in the old days before "Top Tier" was adopted across all octane ratings, etc. Now, because of cost, it is rarely beneficial that way but I like my motors to have clean injectors and pistons and rings intact, my 5.3 drinks either 93 or ethanol. They love burning ethanol too!

As for oil, I switched off of Mobil 1 EP filters years ago for K&N filters with the 1" nut and run the longer PF63 as well. The M1 filters lowered my oil pressure more than my liking. The K&N is tops, nothing out flows it or filters better than it. Now that they're making PF48s and PF63s again, not "E", and now we have 3 LS engines to care for, I may go back to ACDelco filters.

A little while after I switched off M1 oil as well. My motor would rattle on start up and it does not on ACDelco's oil. The stats are better and on par with Shell Rotella's Gas Truck oil.

donjetman · Sep 26, 2022

CruelJung said:
I drive a 2008 Yukon XL, 5.3 1500 Flex Fuel. The vehicle has 170,000+ miles on it and the AFM/DOD is both mechanically and electronically deleted. I am interested in doing my own oil changes and would like to know what oil and filter brands are most ideal for engine health and longevity.

From my current base of knowledge, I am leaning towards a Wix filter and Amsoil synthetic oil (my vehicle has already been running on synthetic, with AC Delco filters). Any suggestions or experience?

Additionally, is there any reason to run my vehicle on higher octane fuel than 87 unleaded?

If you want higher mpg and range run higher octane fuel. I've run all grades of fuel. Knock detectors, variable valve timing, O2 sensors etc make this possible/happen.

I'm running Amsoil ASM Signature 0w-20 and Fram Ultra #10575 filter in our 180+k mile 07 Denali w/6.2L.

I occastionally run a 20-30% e85 mix with premium unleaded in this non-flexfuel vehicle with no negative results. Cost/mile is reduced and I believe the e85 may be doing some cleaning of the fuel system, combustion chamber deposits, valve deposits, and exhaust.

I don't hotrod or tow with our Denali. I get 19 mpg on the hwy and 16 mpg locally.

Here's a thread I did recently with 4 of our most recent used oil analysis reports:

https://www.tahoeyukonforum.com/threads/latest-uoa-0w-20-07-6-2l-w-180-k-mi.136491/#post-1711683

2008 5.3 Engine Oil/Filter + Octane Rating

CruelJung

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iamdub

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CruelJung

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donjetman

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iamdub

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CruelJung

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iamdub

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CruelJung

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swathdiver

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donjetman

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