Is the switch from norm to synthetic really worth it? Here's what I'm running...

87 350 auto with 130,000 miles and currently running 20-40 castrol gtx.

Which synthetic should I switch to (or should I switch at all) ??

Thanks.

 

Mobil 1, Amsoil, Royal Purple are the top ones.

 

Running sythetic will always help, however, the benefits would be maximized on a much newer engine. With that many miles on an engine, and the boosted cost of the synthetic oils, you may not want to run it.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

I run Mobil 1 in mine. I have a 305 with about 160,000 miles on it. It's pretty high mileage, but mechanically the engine is still in really good condition, so I'm not taking any chances.

 

what weight to use?

 

Heh, today I went into wallmart to get the last 5qt jug of mobil1. When I went to the register it rang up as "swisher sweet cigars" "Not a joke For real!!"
2.69$ even though it was clearly market with a price tag 17.88$ 3$ for 5qts of mobil1 doesent sound to expensive to me

10-30w is what our engines require.
SSC

 

I run Mobil 1 15W-50 In my 89 Formula with 68,000 my moms 96 Maxima with 90,000 miles and Mobil 10W-30 in my 99 Grand Prix GT In my other car I run Exxon Superflow 10W-30 with 130,000 miles on My 90 Lumina and hte same on my 98 Z71

 

i think castrol is the only brand that carries 10-40 full synthetic that i knwo of except royal purple, it has a 10-40, but i don't know about Amsoil. thats if u wanna keep running the 10-40 like if it leaks to much or something.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

 

Actually I'm running 20-40...

I was running 10-30 for a while when I bought the car and I'd always be about a quart low by 2500 miles. I upped it to 10-40...still was a little low (but not a quart). I'm now on 20-40 and have had NO problems. The engine has 130,000 on the clock, gets lower than normal gas mileage, and burns a little oil. Just waiting for the thing to go out (and in goes the 383 stroker) So the consensus is either A) I just go ahead and switch or B) don't switch because the engine isn't new anyway

which to choose? any more suggestions?