Is It True
 

I Have A 91 454/b1 And Was Wanting To Use Synthetic. I Was Told By A Mechanic That If I Start Using It Now It Will Leak From Every Seal.is This Something That I Should Worry About.

Re: Is It True
 

Sounds like urban myth to me. Where's his research and data coming from?

Re: Is It True
 

I THOUGHT THE SAME THING THATS WHY I AM ASKING THE EXPERTS.

HE CLAIMS THAT IN ALL THE OLDER MOTORS THAT HE HAS SEEN SWITCH TO SYNTHETIC HAVE DONE THIS.

Re: Is It True
 

I doubt EVERY seal will leak. I have "heard" that synthetic may leak through seals.

If your motor is stock, don't bother switching.

Re: Is It True
 

Your Mechanic is dead wrong. Ask him to explain why. Guarantee he has no real explanation.

Re: Is It True
 

I don't fully understand this however I can tell you that I run synthetic in my 1989 454 bravos without leakage.

I use synthetic gear oil in my 72 SS Chevelle M22 transmission and it leaks through the side cover. It never leaked with conventional gear oil. I don't know if this is related to the particle sizes or surface tension, but I know from experience it leaks in the tranny.

bbcngineer

Re: Is It True
 

THE MOTOR IS STOCK UNTILL NEXT WED. IDECIDED TO GO WIHT 502 ALUMINUM HEADS, MARINE POWER ALUMINUM MANIFOLDS SND RISERS, 750 HOLLEY, MSD, AND A NEW CAM. I THINK THIS SHOULD PUT ME AROUND 450-475HP. WITH THESE UPGRADES SHOULD I USE SYNTHETIC AND WHAT WOULD BE THE BEST SEALS TO USE.

Re: Is It True
 

I had about 175,000 miles on my 94 GMC 1/2 ton pickup with a 350 in it when I tried synthetic. Yes, it seemed like it was leaking badly out of every seal on the engine. I know that there was some seepage before the change but now it was leaving puddles instead of a few drops here and there. I changed back for that very reason. I did, however, change the grease in the differential to sythetic with no leakage at all. No urban myth, just my own experience............and that's all I have to say about that.

Roger

Re: Is It True
 

Synthetic oil typically isn't as "thick" but has superior lubricating properties hence it will be given higher viscosity ratings. That's why sometimes the seals leak. In a sense, if you had a leak before it may get worse because the oil is a little thinner. You can make the same thing happen by switching from a 40wt oil to a 5W 30.

He is probably blowing it out of proportion but there is a "little" truth.

Re: Is It True
 

Thanks I Will Give It A Shot,hope I Don't Have A Bilge To Clean Soon.