GM 6.6L L8T swapped into Suburban, need oil help

[Cpta88]

Hello, brand new to the forum. Just finished swapping my 2018 suburban at 120,000km after getting a lifter knock to a brand new Chevy 6.6 L8T crate motor.

New to the whole idea of running something other than what they recommend. Currently has the break in oil engine was shipped with. What should I go to? I got Motul 5w30 dexos and a Baldwin filter for the first oil change and was going to do another in a week or so.

Motul has a 5w40 euro spec that my friend recommends and digging through here amsoil 0w40 seams to be a popular choice.

Would love some help and reasoning behind the choice. Want this thing to last forever!

 

[redhat]

5W-30 would be fine on this. Lots of the L8T's go quite the distance on it.

However, if it were mine, I'd probably go Mobil 1 FS Euro 0W-40. Better cold start characteristics, has the A40 Porsche approval and a pretty robust additive pack. Plus it's easy to find (Walmart) and cheap at $25 per 5qt.

Cool swap, it's probably what I'd do many many years from now if the L84 in my T1xx Tahoe is in need of replacement. I priced a used one out for my Mom's K2xx Tahoe but I don't know if she'll like the MPG hit.

EDIT: I also forgot to mention, all 3... Mobil 1 ESP X4 0W-40, Mobil 1 Supercar 0W-40 and the Mobil 1 FS Euro 0W-40 all have DexosR approvals straight from GM which in their wording completely meet or exceed the performance of GM Dexos 2, GM Dexos 1 Gen 2 and GM Dexos 1 Gen 3.

 

[userfriendly]

The 2500 & 3500s that come with that engine specify 5W30 Dexos.
I’ve put 0w40 in those engines for better cold start production when it gets below minus 30.
In summer, XW40s.
Edit; See above post. We posted seconds apart.

 

[AZjeff]

That should wake up your Suburban. Any problem with the electronics/engine management? Mobil 1 ESP 0W-30 and 5W-30 are highly regarded around here right now. They aren't Dexos but have great certs. I might stick with a Dexos oil for a few OCs if warranty is a concern and GM specs Dexos.

 

[Cpta88]

5W-30 would be fine on this. Lots of the L8T's go quite the distance on it.

However, if it were mine, I'd probably go Mobil 1 FS Euro 0W-40. Better cold start characteristics, has the A40 Porsche approval and a pretty robust additive pack. Plus it's easy to find (Walmart) and cheap at $25 per 5qt.

Cool swap, it's probably what I'd do many many years from now if the L84 in my T1xx Tahoe is in need of replacement. I priced a used one out for my Mom's K2xx Tahoe but I don't know if she'll like the MPG hit.

EDIT: I also forgot to mention, all 3... Mobil 1 ESP X4 0W-40, Mobil 1 Supercar 0W-40 and the Mobil 1 FS Euro 0W-40 all have DexosR approvals straight from GM which in their wording completely meet or exceed the performance of GM Dexos 2, GM Dexos 1 Gen 2 and GM Dexos 1 Gen 3.

Thanks for the info and I will let you know on fuel mileage. I can already tell it works way less to move the truck around. My 5.3 got better mileage than my 4.8 sierra, we will see how this goes. I had the swap done by a well know LS shop in my area and he tuned it and it is so far EPIC!!

 

[Cpta88]

That should wake up your Suburban. Any problem with the electronics/engine management? Mobil 1 ESP 0W-30 and 5W-30 are highly regarded around here right now. They aren't Dexos but have great certs. I might stick with a Dexos oil for a few OCs if warranty is a concern and GM specs Dexos.

Shop tuned it and so far so good, had to change displacement and a few other things and Tammy shift point, it’s taken my favourite truck I loved and made it that much better.

 

[JavierH19]

Any euro 30 or 40 will be great.

 

[ls1mike]

What transmission are you running?

I used Mobil 1 5W-30 in my 2024. Seems to work just fine.

 

[dfarr67]

If it is a new engine- I would put whatever is recommended until warranty is up.

 

[FranklinJL]

As others have said, Mobil 1 0w40......its the best cheap oil ever made IMHO....works in everything.

 

[Snagglefoot]

Any more details on the swap. ie: transmission details etc?

 

[dogememe]

That’s really cool! But dexos 5W-30 will probably be fine for a long lifespan.