I've read numerous debates on synthetic vs dino, and on which synthetic is best, etc. I'm not trying to open another debate on that. Searches did not turn up much of any use on the title question.

What I'd like to find out, related to an FD, is whether anyone has had instances of synthetic oil use causing oil seals (front seal, rear seal, etc.) to leak in a situation where they did not leak previously while using dino oil.

The reason I ask this is that I have had that experience (synthetic causing seals to leak due to shrinkage, etc., after they were fine for years on dino) with other cars.

I have used dino in my FD for over 50K miles, and am wanting to get some feel for how the seals would react after a change to synthetic.

Thanks in advance for any answers.

 

IIRC, someone here suggested that the anecdotal reports of synthetic leaking might be due to it's smaller molecular structure.
http://www.bobistheoilguy.com/basic_...ion_design.htm
FWiW, this site mentioned additives that some oil formulations use (organic phosphates and aromatic hydrocarbons) that are designed to swell elastomeric seals. There is no mention of these being limited to only mineral oil though.

 

Thanks for the reply. But, I still wonder about changing over possibly causing leaks. I have none now, and I'd like to keep it that way.

Dave

 

I switched a little after 50K, no prob. On my brother's Corrolla I switched after 100K no leaks.

 

In my experience tearing down many many motors, almost all had failed from detonation and a few from overheating. None at all were from oil-related problems, and I'd say 75% of these cars ran synthetic.

 

Thanks for the reply, but what I'm specifically trying to ask is whether a switch to synthetic after many miles on dino caused any oil seal leaks to appear.

I have no doubts about which oil I would like to use if it wouldn't cause leak problems - I use synthetic in all my other engines ('74 Chevy Van - tows my racecar, SCCA Formula Continental racecar, '99 Passat 1.8T, '05 Ford Focus, '85 Sears lawn tractor).

 

On my original motor with ~50k miles (~9 yrs) on it I switched from valvoline vr1 20w50 dino to mobil1 15w50 and noticed only positive effects .

 

I switch back and forth from time to time and have never noticed any new leaks. I started on dino and went to synthetic and now Im back to dino. I figure the dino burns better but thats a blessing and a curse. I go through a quart of dino every 1000 miles where I went through a quart of mobil 1 15w50 every 750 miles or so. It was a small but noticeable difference. Ive even run both at once(need oil now gimme the penzoil style) with no noticed negative effects. Im planning on switching back to syth for my emissions test. Im hoping that syth burns "cleaner" with regards to emissions restrictions not residue or what not. But this is all butt-dyno conjecture and leak checks. My promary blows oil all day every day. Its had a small problem with that for days(read a long time). Its not getting worse yet and neither oil has done better than the other at not leaking through it.

 

Thanks. THAT'S what I was hoping for!

 

Barban,

Thank you, also, for your reply!

 

I switched to Mobil 1 after the engine had 60 K and had only noticed a faster spool up on the engine and turbos.

 

Thank you. That's a good indicator.

 

Thank you. With only positive responses, I think the jury has reached a verdict!

Dave