What is the best oil to use a mulit grade, stright grade or a sinthetic for a 502 MPI 500 HP. eingine.

There is about a 90 page thread on this subject.

There's probably 90 threads too!!

Like most things on here...personal preferences!!!

I know, I Know, I do not want to start the ball rolling however............ I just opened (today) a bottle of Valvoline Racing VR 40 Wt and it is TOTALLY DIFFERENT than the same bottle I purchased two years ago... COLOR AND THICKNESS BEWARE because of the emission and Catalyctic changes and requirements...I will be using Brad Penn from now on.

I'm not impressed with Brad Penn at all. Here's an old post of mine..

I'll share my experiences with Brad Penn oil.
Up until last summer (2005) I had been running Pennzoil 20-50 (engine builders recommendation) I change my oil every 10 hrs and it seemed to work pretty well, no oil pressure issues, oil temps @230 after an occasional hard run 260 (measured before the cooler)
Toward the end of last season I had switched to Brad Penn 20-50 and was not very impressed to say the least. In June I trailered over to Lake Winnipesaukee for Laconia weekend.I had just done a fresh oil change for the trip. We did a lot of boating the first couple days. After three days of running Brad Penn (8 hrs run time) I noticed a loss of oil pressure. My boat normally runs about 60 lbs after warm up while cruising. We were cruising along at no more than 4000 rpm when I noticed the oil pressure dropping. It dropped to 40 lbs, then 30 lbs, I backed down to 3500 and pressure dropped to 20 lbs.
I thought It was engine trouble and stopped for a while. Upon restart, oil pressure returned to normal, 60 psi but soon dropped back to 20 after temps warmed up to normal.
It appears that the Brad Penn oil was all done at 8 hrs and was breaking down at less than 220 degrees oil temp.
I've since changed to Mobil 1 (V-Twin) and all has been fine since. The Mobil oil seems to be pretty consistent, no pressure fluctuations at all and more oil pressure.

Take it for what it's worth, just my personal experience.

Kurt

The above post was from 9/06 I've been running Mobil 1 V-Twin ever since. Oil pressures are not affected by oil temp with this stuff. I'm sold!

Kurt

http://www.offshoreonly.com/forums/s...ight=brad+penn

M-1 V-Twin seems to really solve many oil related issues and offer great protection.

Try 15W-40 Royal Purple synthetic and you'll be hooked. Your engine will love you, you'll make more horsepower, you will run cooler due to less friction AND if you ever have salt water intrusion, the engine can be saved.

Kendall 20w-50
http://tds.econocophillips.com/catal...0TDS%20Web.pdf

I would like to switch to a synthetic oil, but my engine builder won't warranty unless I use Valvoline Racing 40W. Hope I don't damage anything while under warranty.