i have been running mobile 1 5w-30 since i got my car about 12k ago. it now has 91k on it. im thinking about switching to 10w-20. what do you guys think about this?

 

Why would you want to switch?

I've ran the 5w-30 for over 4 years and 60k since doing my heads and cam. I am in the process of refreshing my valvetrain. The lifter valley along with the heads and underside of the valvecovers are amazing. They are completely spotless, just as clean as they were when I installed them. I am 100% sold on Mobile 1 synthetics. Not bad for an engine with over 100k miles. I can still see hatch marks on the cylinder bores!!

Mike

 

I think it's s good idea. There was a discussion here a while back about how 5-W30 is too light for the LT1. Especially with high miles on it. There's a special Mobil 15-W50 made for Mercedes that is supposed t be a better weight for the LT1. I switched to the 20-W50 last year and it brought my oil pressure up about 15 psi. Now I have 35psi at idle and about 50 psi at high rpm.

 

is that really a good thing? maybe losing some peak hp
what's wrong with 10W-30 or just straight 30?

 

I use Pennzoil 10W30 in mine. When I first start the car in the morning, I read 70# . It drops to around 40#/idling/hot. That's with a stock pump on a 95,000 mile bottom end...LOL

Frank