What weight oil does everyone run?
Thread Starter
Teching In
Joined: Jan 2006
Posts: 19
Likes: 0
From: Frankfort, IL
What weight oil does everyone run ? I have always been a fan of 20w-50 oil in my old school 350 motor for the summer, and I would feel better running it in my LS1. It bothers me having 30-35 psi warm at idle and only having 45 while cruising. The owners manual of my 98 Trans Am says to run 5w-30 or 10w-30. It says not to run 10w-40 or 20w-50. I heard some people saying that they run 20w-50 in their LS1's. The thicker oil should quiet cold start up piston slap but will it hurt anything else other than a slight power loss due to thicker oil ?
Originally Posted by 92RS98TA
I have always been a fan of 20w-50 oil in my old school 350 motor for the summer, and I would feel better running it in my LS1. It bothers me having 30-35 psi warm at idle and only having 45 while cruising. The owners manual of my 98 Trans Am says to run 5w-30 or 10w-30. It says not to run 10w-40 or 20w-50. I heard some people saying that they run 20w-50 in their LS1's. The thicker oil should quiet cold start up piston slap but will it hurt anything else other than a slight power loss due to thicker oil ?
TECH Apprentice
Joined: Jul 2005
Posts: 374
Likes: 0
Newer engines are built with newer technology. Today they can be built consistantly with closer tolerances than older engine designers could have ever dreamed of. I had a problem adapting to the newer engines too, (5w30 from the factory) until I realized that they just don't need the thicker oils to get the job done. The car companies of today had to get their acts together because of ever tightening emission standards, fuel economy standards, and consumer demand. Motor oils have also improved drastically and it takes more energy to drive an oil pump that's pumping 20w50 through your engine than one pumping 5w30. That's one of the reasons they went to the thinner oils (better fuel economy through decreased pumping losses) Eventually you'll get past your mental block (I know I had to) of an engine needing 20w50, and accept the fact that it's a whole new breed of engine. Just run a premium synthetic motor oil that's on the lighter side and you'll be fine. The Castrol Syntec 0w30 that specifically states "Made in Germany on it's label is an excellent motor oil to use in the LSx series of engines. 
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