1976 GMC Royale

[Dehaka]

So my mom just got grandpas 1976 GMC Royale RV Motor Home. It has a new reman engine going into it. It's probably gonna drive up and down California and not much else. What is the absolute best choice of oil to use regardless of price to keep it running clean, strong, and long?
What would the absolute best oil filter brand to put on it?

25+ grand is being poured into this thing and I want my mom to have the best info regarding engine oil.

Thanks

 

[JavierH19]

I'd pick any full syn hdeo or similar euro grade oil of the walmart shelf. If it were mine i'd see myself using delvac extreme 15w-40 or even the regular delvac 1300 as that's still plenty good.

 

[Graham Piccinini]

I would say HPL or Amsoil, but if she needs it in a pinch - it's not in any stores. Has to be bought online and shipped.
So instead I will say Mobil1 FS 0W-40. Available anywhere she travels to, any Wal-Mart or auto parts store will likely always have it.
Edit: Posted at the same time as @JavierH19, and I agree with the recommendation on the Delvac Extreme 15W-40.

 

[Egg_Head]

Does that have the Olds 455 Rocket motor?

 

[Dehaka]

Does that have the Olds 455 Rocket motor?

I just know its the gm 455

 

[Egg_Head]

Is it stock or have you considered helping it breathe? i.e. dual plane intake, headers, etc.

 

[JavierH19]

I just know its the gm 455

What kind of gm based 455 as there's an issue with the olds and i believe the Pontiac 455 in that they can become oil starved from the oil not returning down to the sump when revving past 4k, and that's something you gotta do in a shipping container to get it up to speed. Could've been the reason why it failed. Don't wanna have it swapped out with a 454 instead? because i would to be honest. 1 digit difference but it doesn't suffer from that problem.

 

[PimTac]

There is no best.

Where did this reman engine come from?

The typical oil back then was 10W-40. That would be a starting point. The suggestion for 15W-40 is a good one.

 

[CorvairGeek]

These were only Olds 455s until '77, then the Olds 403 (shorter deck, smaller main bearings) was used, IIRC.

 

[MSCH]

old Big Block gasser in the heat and under load... 15w40 or 20w50 would be what I used.. Filter doesn't matter very much, with the fuel economy of those things you probably can't afford to buy enough gas to wear the sucker out.

 

[MSCH]

What kind of gm based 455 as there's an issue with the olds and i believe the Pontiac 455 in that they can become oil starved from the oil not returning down to the sump when revving past 4k, and that's something you gotta do in a shipping container to get it up to speed. Could've been the reason why it failed. Don't wanna have it swapped out with a 454 instead? because i would to be honest. 1 digit difference but it doesn't suffer from that problem.

it would have been the Rocket Oldsmobile engine in those old buses... aka it is a Toronado Drivetrain. similar to the Eldorado Drivetrain except olds instead of Caddy v8

 

[ChrisMU]

What kind of gm based 455 as there's an issue with the olds and i believe the Pontiac 455 in that they can become oil starved from the oil not returning down to the sump when revving past 4k, and that's something you gotta do in a shipping container to get it up to speed. Could've been the reason why it failed. Don't wanna have it swapped out with a 454 instead? because i would to be honest. 1 digit difference but it doesn't suffer from that problem.

The Olds 455 has a different bolt pattern. No TH-425 FWD transmission was made for a Chevy engine. The only other engine that would possibly work without significant modifications would be a Cadillac 368/425/472/500 (as that engine family was in the FWD Eldorado) and they don’t particularly like to rev, either.

 

[Creekside]

I’d take whatever recommendation comes from the rebuilder to start with. After that some synthetic 15w40 would be fine.

 

[JavierH19]

it would have been the Rocket Oldsmobile engine in those old buses... aka it is a Toronado Drivetrain. similar to the Eldorado Drivetrain except olds instead of Caddy v8

Oh that's true. Forgot about that oddity.

 

[userfriendly]

Oh that's true. Forgot about that oddity.

Called the BOP bolt pattern. Buick, Olds n' Pontiac.
Some motor homes came later on with a Cadillac engines.
I'll put money on this 455 being a 68 and newer Olds.

 

[MSCH]

Oh that's true. Forgot about that oddity.

not really an oddity, that engine was around for quite a time period in various displacements

 

[SR5]

I would use a dual rated 15W40 HDEO like Delo, Delvac or Rotella.

Otherwise a Euro rated 40 grade, as in A3/B4 rated in 0W40 or 5W40, such as M1 or Castrol Edge or Pennzoil Platinum Euro.

Keeping it simple, you can get M1 0W40 everywhere and it's top shelf.

 

[Dehaka]

There is no best.

Where did this reman engine come from?

The typical oil back then was 10W-40. That would be a starting point. The suggestion for 15W-40 is a good one.

Some big specialist out of Washington State.