Mobil 1 Oil Leaks

jlkline · 12-08-2002, 06:12 AM

About 2 months ago, I bit the bullet after a lot of soul searching and reading forum threads on the subject, and changed to Mobil 1 (15W-50W)with about 11,000 miles on my completely rebuilt 3.2 motor. After around 3 months, it has begun leaking in various places including the valve cover gaskets (930 covers), bolts around the rear pulley, and other places on the motor, mostly at the rear.

I'm looking for some advice on what corrective action I can take that will stop the leaking. Should I:

A. Stay with synthetic and change brands / or viscosities?
B. Go back to dino oil?
C. Other options?

If I stay with synthetics are there some less prone to leak than Mobil 1, or is this just the nature of the beast?

What about the dino/syn blends? Is there significant advantage over straight dino to justify the price, and are they leak prone as well?

I'm leaning towards going back to dino, but I sure would like the to have the extra protection of synthetic in both cold and the 100+ Texas summers

Joeaksa · 07:15 AM

Have been running Mobil 1 on my 85 3.2 for the last 5 years and not one leak other than an oil return tube. Switched to syn oil when living in Dallas for the same reason you mentioned.

Checked with my records and the oil return tube that started leaking had been resealed over 10 years before so no surprise there. Other than the oil return tubes, my motor has never been apart so that may be the main difference.

Sorry to hear that yours is leaking but had to comment. Every so often there is a posting that running syn oil caused their motor to leak and I have not had that problem with three 911's over the last 20 years and none of them used dino oil.

You might try new gaskets and checking the torque on your valve covers but the other leaks may be more difficult to cure.

Joe

carnut169 · carnut169's Garage

I have been using Mobile 1 in my 87 for 2 years now without so much as a drop leaking. If regular oil does not leak there are some really good oils out there... ready to do some reading? Check out my posts on this thread and pick your poison!
Oil info thread

yelcab1 · 12-08-2002, 08:12 AM

I used Synthetic in my 3.2 and it leaks out at the Flywheel Main seal. I put back in the Kendall 20W50 and it does not leak. It's one of those things. They don't always do that, but they sometimes do.

I would (if it were my car) stick to Kendall and change the oil more often, moving the weight of the oil according to the temperature of the environment.

tmctguer · tmctguer's Garage

search for threads on this subject. there are many postings that attest to the fact that a switch to synthetic oil caused leaks where dyno oil had not leaked before. there was a round of postings within the past 30 days speaking to the pro's and con's of a change from dyno to synth.

read all the posts, then make up your own mind.

i suppose another way to look at it is that you will be able to spend more time working on your car than before resolving new leaks. if you like wrenching, this could prove to be fun.

jlkline · 12-10-2002, 03:38 PM

Thanks, everyone for the feedback.
I decided to go back to dino during my valve adjustment service ...Castrol 20-50 which was what I used before Mobil 1. So far no more leakage....for now, at least.

I'd rather live with a little less protection(and not much less with 3K change intervals) than have my beautiful motor leaking like a seive onto my heat exchangers as well as my garage floor.

Unless someone invents a synthetic with the same leak resistance as dino oil, I don't plan to use this stuff again.

beepbeep · 12-10-2002, 04:45 PM

Well, synth doesn't leak more, but it does flush all sludge that dino-oil accumulates.

To put it this way: it accentuates already existing problems with non-tight seals that migh be masked by deposits of dino-oil.

For a N/A engine, it's probably OK, but i would never put dino into turbocharged car.