I know this subject has been covered beforebut.. any sugestions on what weight Mobil 1 to run in my 87' 454's with 500+ hours

I ran 15w50 M1 in my 454 mags.

why change now?

My personal opinion would be to first make sure you don't have any leaks anywhere. Engines with that many hours on them may have some leaks. If you switch to a synthetic, such as AMSOIL or Mobil 1, the detergent packages in those oils can clean any build up, which can possibly lead to leaks. If you're not worried about that, then I would go with the above, either AMSOIL 15w-50 Dominator Racing Oil, or Mobil 1 15w-50.

I say go with Valvolin racing VR1 20/50 reg oil.

have the price and very good.

I have been using Merc 25W40 and found that the price of the M1 wasn't much more and may benefit from the synthedic, my motors are clean with no leaks so I should be ok

Mobil 1 15-50 is the same price as merc oil if you buy the 5 qt jugs at walmart. I can tell you that when I switched to M1 in my 502mpi's, my oil consumption was cut in half. The prior owner had always run conventional oil.

Mobile 1 15W-50 is what I run in my 540's. I change it every 30 hours. Looks like new, but good insurance. I have used it since day one in the motors.

I would do it no problem, I started my 454 at 350 hours on 10w-30 royal purple and ran it till over 1000 hours with no issues, I think it's a good move on boats as they work hard all the time and may help economy as well....even run it in my genset....Rob

WallyWorld 15W-50 M-1 SilverCap

If you race then M-1 20w50 V-twin
Redline 20W-50
Amsoil 15W-50 Racing
RP 20W-50
Motul 15W-50
Valvoline 20W-50


All excellent with a M-1 or Amsoil filter.