5w20 in LS1

[Gary Allan]

Originally Posted By: Ryan02SS
This is my experience with UOA's on my LS1. I have a 420rwhp@396rwtq H/C 02 LS1 SS. CNC heads, small TR224 cam, all supporting boltons, headers, intake TB, etc....
Rev limiter is 6800rpms and shifts for max power are at 6500rpms.

Out of 8 UOA's 15W-40 Mobil Delvac showed the best wear control compared to Mobil 1 10W-30 and Schaeffer 10W-30. IMO For a hard run performance application thicker is better. The same thinking is used in the marine world of engines. 40W and thicker is standard to keep the engine alive.


Heck, throw on a supercharger and you'll have even more justification for heavier oil

Now let's take our common GM engine that specs 5w-30 and compare it to an LSI that specs 5w-30. GM seems to think that the vast difference in power output works just fine with both engines using the same oil weight. I imagine that if GM put out an engine that had all the goodies that you've got ..putting out all the rwhp that yours does ..and could actually sell it in a federally certified manner ..make the warranty period and beyond ..it would still spec 5w-30. You're the one stretching out the output beyond the engine's capability to manage itself with the regular oil weight. I hardly call that a reason to support the heavier is better theory.

Now dry sump it ..drill out all the oil passages ..dial in the pump so that you've got the same pressure at higher volume (or whatever) ..and I say that you'll do just fine on any weight oil

 

[Merkava_4]

Quote:
I hardly call that a reason to support the heavier is better theory.


That may be, but it was refreshing to read a thick post for a change.

 

[Panzerman]

I got the lifetime warranty from Dodge on my Hemi, so this last oil change I went reluctently to a 5w20, for which is spec'd, I went with Havoline Full synthetic 5w20, so far, I see no increase in fuel milelage and it doesnt seem alot peppier either, than the Castrol GTX 10w30 that I put in it since new. Ill probably go back to the 10w30, after my stash is used up, its just too hot in Florida and I cant see why 10w30 would not do anything that 5w20 could do in warm weather. This truck is not MDS and I cant see any advantages if my fuel milelage stays the same.

 

[Whimsey]

Originally Posted By: Merkava_4
Quote:
I hardly call that a reason to support the heavier is better theory.


That may be, but it was refreshing to read a thick post for a change.

Merkava, While I use 5W-20 in my 2002 4.6 F-150 and my wife does in her 2005 4.6 Exploder I still use the "thick" 5W-30 oil originally spec'd for my bought new 1996 4 cyl Zetec Ford Contour

. I use Schaeffer's Supreme Blend. They didn't back spec that engine for a while after 5W-20 came out unlike most other Ford engines which were back spec'd. So I was leary of using that "thin" 5W-20 oil

. It's my poor man's "BMW" and I drive it hard and fast, it's a 5 speed manual with the factory wide aluminum wheels. For a "cheap" car it's a blast to drive hard if you have the manual tranny and wider wheels.

Before BITOG I thought "thickerer was betterer". So I used Castrol Syntec 5W-50 in the Contour. Well it revved slower was sluggish and the mpg went to heck. I went back to 5W-30 and it was SOOOO much better. I'm sure some engines are better with thicker oil but not many NEWER AMERICAN manufactured vehicles work better or need thick oil.

Whimsey

 

[buster]

I'd like to see M1 0w-20, Amsoil 0w-20 or RL 5w-20 in a LS2.

 

[Win]

I sure would not run it in mine.

It seems to me that because of CAFE it would be to GM's advantage to spec 5/20 if they thought it proper, but they do not and I am not inclined to second guess their judgment.

From a subjective standpoint, at about 20K miles, my LS1 sounds happiest on the Lucas 5/30 synthetic that was vigorously panned down in the VOA forum.

 

[BigBadf350]

some good points being made here. now we just need some UAO's to back them up.