Will switching to Mobil 1 result in more leaking?

[Rick Lee]

I know this topic arouses fierce opinions and it's probably been covered before. But I'm slowly coming up on an oil change and would like to go to Mobil 1. Mine is an '87 Carrera. I've been using Castrol. The problem is I have a very slight leak at the lower left cam cover. I've heard that switching to synthetic lube tends to find new or exacerbate existing leaks. That did happen on my BMW and it was fine when I went back to Castrol. I don't know how big a project replacing the cam cover gasket is. But is Mobil 1 gonna make it leak even worse? Castrol has done fine for me, but that Pelican tech article on synthetic lubes was pretty convincing. Should I stick with Castrol or take the synthetic plunge? Thanks.

[Matt Holcomb]

Richard,

What about semi-synthetic oil? That's what I'll be putting in my 2.7 race motor.


Matt Holcomb
1974 911 Carrera 2.7 Euro
1975 Mercedes-Benz 280SE
Dedicated Homepage
Engine Rebuild Homepage
Porsche Owners Gallery Profile
Pelican Gallery Profile

[Early_S_Man]

Richard,

Are you talking about a leak at the lower valve cover, or the chain case where the tensioners reside? I have the feeling that leaks will be worse with Mobil 1, but valve covers are usally fixable, either by using the proper torque on the nuts (not overtightening the way a lot of people seem to do) or perhaps changing to the red silicone 'permanent' style gaskets from the 'Real' Gasket Corp.

If, however, the leak is at the junction of the chain case and the crankcase, I don't think there is much you can do about that one with the engine in the car!

------------------
Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

[tmctguer]

Early S Man:

elaborate on your comment about a leak "at the chain case and the crankcase". are you referring where the chain tensioner case connects to the engine block?

if so, what IS the fix for a leak of that nature?

[Rick Lee]

I'm not sure, but I was told my leak was at the lower cam cover. Whatever it's called, it's about 90 deg to the back from the left lower valve cover. I was told it was nothing to worry about, though it drips onto the heat exchanger a little, and smells as such. I'd need a much better reason to drop the engine.

Regardless of where the leak is, is it likely to become worse with Mobil 1?

[Early_S_Man]

Well, yes, my experience when I put Mobil 1 in my engine was that seepage/weeping became drips.

My fix for a leak at the junction of the chain case and crankcase is to be a top-end 'freshen-up' job ... though I suppose you could just pull the heads and camshaft housing, then replace the chain case gaskets and head gaskets/sealing rings and reassemble and seal with Loctite 518.

------------------
Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

[VenezianBlau 87]

FWIW, I started using Mobil 1 15W-50 in my '87 Carrera five months ago and still no leaks.

The Mobil 1 was used for two months before I changed out the gaskets following a valve clearance adjustment. No leaks on old gaskets or the new ones.

Also, I replaced the gear oil a month ago with Mobil 1 product and no leaks.

Good luck!
-------------
Bob

[campbellcj]

I still run dino oil in my 911, but I switched to Mobil 1 in my 914 a month ago and haven't noticed any problems, leakage or otherwise. The car is track-driven and runs pretty hot -- I am 100% happy with the switch so far.

------------------
Chris C.
73 914 2.0
70 911E Targa
campbell.chris@gte.net

[GIBSON]

My experience has been along the lines of Warren's, a seep becomes a leak, except in one instance. I have an 87 Carrera which had no leaks, changed the oil and within one week every oil return tube seal failed (or leaked extensively). I replaced the seals but never had the guts to go back to Mobil 1. It probably would be fine but I have not tried. Many engines make the switch with no problem, especially newer cars. It is an excellent oil. If the problems are valve covers, that's an easy fix. Other places may prove more problematic.
Warren, what are you going to use after your top-end refresh this winter? Break in with standard and switch to Mobil 1?
Bruce Herrmann

[cab83_750]

I use Mobil-1 on my Porsche. However, I do have a professionally rebuilt engine. Super clean so far.

I've been using full synthetic since the 80's or so. My rule has been.....

Use Mobil-1, if no leaks, great and stick with it.

If M1 leaks, use Castrol (synthetic, of course!) I think Castrol came in #1 when rated/tested by Consumer Reports.
1. Small leak will become drips.
2. Hard to explain, but I smell