What type of weight oil should i run a 454 merc 330 horse motor.

Straight 40w

I'm running 30w in my 454mag 365hp is that good or bad? With STP.

You should run a 10w-40 or a 20w-50, or something in that range.

A good Straight 30 or 40 if you run wot a lot.

Never use stp or pennsoil if you have ever taken a motor apart that this $hit was put in you would know why. They are carbon sludge makers.

I was going to say about the same. I hate additives. If the oil was supposed to have it in there, it would already be in it. That is why I use the AMSOIL TRO 20w-50 Racing Oil.

http://www.amsoil.com/storefront/tro.aspx

shell rotella t - 15/40 best oil period.

Firehawk,

Sorry to go off topic on you, but seems like the oil question got answered. That avitar looks familiar. I took a ride about 20 years ago in a prototype Mustang built by Jack Roush that had that exact same body work and wheels. Was powered by a 351 with GT-40 heads and twin turbos. Same car?

The car in that avatar is a production 1993 Mustang Cobra. They only made that model one year. I think they had about 5 - 10 more hp than a stock GT, and had a different body kit. They still seem to bring big money in good shape. There were some R versions available to race teams only I believe. They were a no air, no power option deal, and they were stripped down for weight.