what is the best brand of oil for a v8 305 tpi engine from my 1986 trans am that has 100,000 miles on it?

at the moment im using castrol gtx high milage

and which WD mix should I be using?

and Should I switch to Mobile 1 for more synthetic?


any suggestions would be appreciated

 

This is a well debated topic. Searching would help you out. Best oils are pure synthetics. (i.e. Mobil, Amsoil, Royal Purple, etc.).

 

The "good" synthetics are PAO or Group 4. Unfortunately, you can't tell from reading the bottle whether it's PAO or highly refined petroleum, Group 4 or Group 3.

AMSOIL except the XL series, and Mobil 1 except the high mileage series, are PAO.

The "high mileage" oils have extra plasticizers in them that are supposed to soften up seals to make them more pliable. Problem is most SBC valve seals harden and crack after long exposure to petroleum based oil and heat, so no amount of plasticizer is going to "fix" them. The other problem is when you add something to a quart of oil, something has to come out - what did they take out of those high mileage oils so they could put plasticizers in?

It's a safe bet to go ahead and replace the valve stem seals. If you develop other leaks, fix what's leaking. Don't depend upon an additive to fix it.

 

im asking because i want my engine to last for as long as its gona last. i have no money left for a new engine at this time.

so if theres anythign i can do to help things i'll do it. like good lubrication oil for high milage engine.

etc.... not looking to fix leaks because i dont have any and i already repalced my valve cover gaskets

 

Anything that claims to be "synthetic", and doesn't have a mile-wide viscosity range (like 0W-50) is going to be better than most any petroleum based oil. I would recommend AMSOIL, Mobil 1, Redline, or Royal Purple, in that order. I'd only go with Quaker State, Penzoil, or Valvoline synthetics if I planned on changing the oil as often as I would with petroleum oil (which I don't with AMSOIL).

High mileage oil will not help your engine last longer. If that sounds contrary to you, reconsider what I said about what has to come out of the quart.

 

I'm a fan of Amsoil and Mobil 1. BUT with proper maintenance, even regular old dino juice will carry your engine easily into the 200K mark.
My parents had a Datsun that my dad bought new. The body ended up rusting out of it before the engine leaked or took a dump. He put the car to rest with 253K miles.

 

I couldn't agree with the proper maintenance more. I worked on a Chevy 1500 with 250K on the clock and it had never had anything more than an intake and valve seals replaced, it was a company truck and was maintained religiously at 3-3500 miles no matter where it was (which was usually every week and they used the cheapest oil and filter available). This truck had a 4.3 (which by itself is an accomplishment to last 100k without major surgery) if you would have driven it you would have thought it was a low mileage mill. As with any vehicle take good care of it and it will take care of you.