Thread: Any advice on oil weight

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Hello, I was looking for some advice on what weight oil I should be using in my hot rod. I currently have 5w-30 in there now. When the car is cool I have about 40lbs of pressure at idle, once the car is warm it drops to about 20-25lbs at idle. I was wondering if I should use a thicker oil such as 10w-30 or even thicker. The engine is a 69 sbc 350 with a 471 blower on it. The car seams to run at a good temp around 180. I won't be driving the car in cold weather so that won't be a factor either. I even installed another guage on the block to do a comparison and they run about the same. any advice would be appreciated thanks.

Actually, I'd say it's about normal for a sbc at idle.... Heavier oil might be better for it, depends on which school of thought you go with on oil. Personally, once the break-in time is over I run all mine on synthetic Mobil 1. Not near as affected by temperature as dinosaur oil, never have had an oil related failure with it, either. That includes 5 seasons of circle burnin' and 20+ years of drag racing.....

Multi-viscosity oils are formulated to emulate the properties of thinner oil when cold and thicker when hot. A 5W-30 has a viscosity of 5 weight cold, and of 30 weight when hot. The newer 5W oils were formulated for better economy (less drag) in tighter engines to improve efficiency. You should see no difference in your operating pressure between 5W-30 and 10W-30 as they are both 30 weight hot. You might try 10W-40 for one cycle and see it that gives you any better hot pressures.

Here is a great site with all the answers you could ever need about oil.

http://www.bobistheoilguy.com/

They also have a good forum.

http://www.bobistheoilguy.com/forums/ubbthreads.php