DINO vs SYN OIL = LEAK

[lindy 911]

I changed my break in oil from GTX with Joe Gibs break-in additive to Champion synthetic 20 / 50. The nose bearing O-ring now leaks, it did not before the change. It's not just a little. It's coming from the top right quadrant of the case-to-bearing joint. It will require a complete tear-down to fix.

As a last ditch effort, before I pull it all apart again, I added some o-ring / seal conditioner to the oil to see if that might help; no go.

Anybody know why a synthetic would leak but the dino did not?

Lindy

[brads911sc]

Wow. That sucks. Sorry about that.

Lots of stories on both sides of the debate on that. Doubt it was caused by the oil per say but the multi grade oil (either dino or syn) have different properties than the straight weight low detergent break in oil. Just my .02.

I will use Kendall GT1 or Valvoline VR1 dino in my new rebuild.

[JFairman]

Try going back to Dyno oil and see if the leak stops. Brad Penn Racing oil is the usaul favorite 20w-50 Dino oil.

[YTNUKLR]

This has been said before and I think synthetic can make the oil seals shrink.

Did you use any sealant on the nose bearing

[snbush67]

Lindy,

My engine (prior to rebuild) was dry until I decided to use Royal Purple Syth. Then it sprung a cam seal leak. I changed back to dino and it still leaked.

I think synthetic gets by worn or old seals that dino wouldnt.

After break in on my rebuild I am using Amsoil 10/40 Synth., no issues, everything is holding together with no leaks.

Sorry to hear this happened.

Shane

[JJ 911SC]

As mentioned in Project 2 of Wayne's 101, older car with older seal should stick to dyno.

The PO was on synthetic and had multiple leack. As soon as I switch to BP20/50, no more leak.

[lindy 911]

I appreciate all the advice. It seems that there is an issue though with the nose bearing o-ring. I did not glue it in as Henry suggests. I learned of Henry's sealing advice about a day AFTER I put my cases back together. It's really not all bad as I actually like the tear-down / re-build process.

The thing I can't figure out though is why did this leak take so long to surface? I've had other leaks that I could fix pretty easily but this one is strange. I don't think the theory of old seals being affected by synthetic oil is what's happening here because the seals are virtually new.

Lindy

[YTNUKLR]

Have you ever put a rubber seal in some mineral spirits

even a new one will swell up to twice its size...something like this probably happens with dyno oil, and thus makes a seal tighter..

synth doesn't have those agents in it, so the seal shrinks to "normal" which may not have been tight enough to keep it from leaking

that's my story and i'm sticking to it!

ps. i recommend henry's threebond 1211 on the nose bearing, i've never had a leak there in 10 motors

[AlfonsoR]

Lindy,

If you don't mind, would you post pictures of the engine and nose bearing going back together as per Henry's seal installation directions?

I did not know about this either and it would be good for other folks too, I would imagine.

On the oil question, I think anyone who says anything at this point is just guessing. However, I would just stick to something that is known to work in these engines such as the Brad Penn. I guess you went away from Castrol because of the Ultimate Oil Thread?

[lindy 911]

Go to the "Complete engine sealant thread". It has all the info about where and how to apply what. Scroll down and you'll find Henry's recommendations. Henry is King as far as I'm concerned. There are others here that know their stuff too, no doubt, but Henry has never steered me wrong. Unfortunately, I didn't find the thread until the day after I put my cases back together.

Lindy