Oil recommendation - high mileage GM LY6 6.0

[intheburbs]

My 2008 Suburban 2500 has 160k miles on it. I bought the truck with 100k miles, had good compression in all cylinders when I bought it, and I've always used synthetic for my oil changes - either Royal Purple 5W-30 or Mobil 1 high mileage 5W-30. I've never done a used oil analysis.

I'll be taking a trip this summer where I'll be towing an 8600-lb trailer to Yellowstone. Will be about a 4000-mile trip over two weeks. I've towed slightly lighter trailers with this truck previously.

My search skills aren't the greatest, but I didn't find much on either 3/4-ton Burbs nor the LY6 engine. What would you guys recommend? I've kind of moved away from the RP, using M1 more often now, usually 5,000-mile intervals. I just want to make sure I'm not missing anything out there.

Thanks!

Pic of family (wife and 3 kids)and rig:

 

[dareo]

I would probably do the M1 5w30 as well. I run 0w30 in my 6.0 gmc but it currently sees light duty use.

 

[WiskyBadger]

Mobil1 HM seems perfect to me.

 

[oil_film_movies]

Mobil1 HM 10w40 since you are towing like crazy there in the summer. Extra high temperature protection (HTHS 3.9). HM oils do have the extra seal conditioners too.

 

[intheburbs]

Originally Posted By: oil_film_movies
Mobil1 HM 10w40 since you are towing like crazy there in the summer. Extra high temperature protection (HTHS 3.9). HM oils do have the extra seal conditioners too.


Good tip. Thanks. Hadn't thought about the effect of the higher temperatures.

Last time we were out West in July, we experienced these kind of temps (this was White Rim Drive in Canyonlands)

 

[oil_film_movies]

Also, using M1 HM 10w40 (or any brand full synthetic HM oil 10w40) would give you some ability to endure viscosity reduction from fuel dilution in blowby from running high loads. That engine can take a lot more fuel dilution if you start with a 10w40.

 

[Chewie]

With that much towing, I'd look into drain/fills of your transmission and diff as well.

 

[intheburbs]

Originally Posted By: Chewie
With that much towing, I'd look into drain/fills of your transmission and diff as well.


Done and done. I'm very anal about maintenance. I even just had the power steering fluid changed, since this truck has hydroboost brakes, not vacuum assisted.

Trans fluid was replaced for the second time since I've owned it earlier this year, and the axles were done for the third time earlier this year.

 

[BobsArmory]

Fresh trans fluid would be a great idea. M1 High mileage would be good as well.

 

[Nickdfresh]

I think as you're using quality synthetics at very conservative intervals, the weight and brand of the oil is the least of your worries. I'd be far more concerned about the cooling system and as said above, the trans and differentials...

 

[slacktide_bitog]

cool truck! Do you have the barn doors?

Any synthetic for the OCI suggested by the OLM will serve you well. But my choice would be Napa Synthetic, which is on sale for $3.49/qt, if you like Valvoline

There's certainly nothing wrong with M1 and RP though.

 

[BrocLuno]

Originally Posted By: oil_film_movies
Mobil1 HM 10w40 since you are towing like crazy there in the summer. Extra high temperature protection (HTHS 3.9). HM oils do have the extra seal conditioners too.


+1

That motor will build some serious heat towing out west. I'd have the tranny serviced before I left too. And I'd fill the rear end with Red Line Shock Proof Lite.

Brakes good? No loose suspension bushings?

 

[Carbon12]

I don't think you could go wrong with Mobil 1 High Mileage in either 5w30 or the 10w30 with its higher HTHS of 3.5

I am not sure if your suburban is old enough to be affected by this issue, but take a close look at your brake lines (the metal ones that run along the frame). If they are rusted have them replaced. I have 2003 GMC Sierra that I bought a few years ago. I bought new ACDelco replacement lines from Amazon for about $70 and had an independent shop install them for about $250 or so. Hopefully your 2008 does need this yet, but wanted to pass this along since you will be towing on a long trip.

 

[Fraser434]

Mobil1 0W40 is well known for its use in LS engines and good UOA's, its pretty thick even when cold. I'd consider that. Or 10W-30 diesel oil, Rotella T5.

 

[4WD]

M1 10w40 HM ... take care of that baby in case the Secret Service needs it back.

 

[Shannow]

Originally Posted By: Carbon12
I don't think you could go wrong with Mobil 1 High Mileage in either 5w30 or the 10w30 with its higher HTHS of 3.5


I like either suggestion...prolly the latter.

 

[64bawagon]

I think you have a solid maintenance plan already in place and with all you've done its to the point of overthinking it. Enjoy your trip.

 

[intheburbs]

Thanks for the suggestions, guys. This truck works hard, so I try to take care of it as much as I can. The coolant (the orange stuff) is only a year or two old, and I just replaced the upper and lower radiator hoses, just to be safe.

Originally Posted By: 4WD
M1 10w40 HM ... take care of that baby in case the Secret Service needs it back.

The truck actually looked like that when I bought it - dark blue, debadged, 5 or 10% limo tint all around. Buddy of mine works with the Secret Service, and he laughs because whenever the President comes into town, he has four or five trucks just like mine show up in his parking lot.

Thanks again!

 

[4WD]

I'll be darn - bet his have mostly air miles

 

[umungus1122]

Mobil 1 0w-40 or 10w-30 High Mileage. Don't forget the rebate.