Synthetic or Fossil in My '89 Carrera

911Bliss · 05-03-2006, 12:52 PM

Previous owner changed to Mobil 1 @ 32,600 (August 04). I'm going to change the oil (34,100) but the service Mgr at the Porsche dealership is recommending switching back. He feels that synthetic may lead to seepage and even leaks do do to the fact that these engine seals & gaskets were not designed for synthetics. Just wondering what you folks are using in your Porsche's.

Thanks,
Ray

Netspeed · 05-03-2006, 01:08 PM

Make sure you do a search. You'll have enough reading material for about 3 weeks.

Personally, I use the fossil stuff.

M.D. Holloway · 05-03-2006, 01:18 PM

Mobil 1 - primarily PAO base stock will tend to leak out of older seals but an 89? Hmmm. Allied Signal, Parker Hannifin and Bosch did a pretty good job of reformulating their seal polymer technology back in the mid 80's to thwart that sort of thing. a Blend may be the way to go - a good oil will have the best of both worlds - oxidation and acid resistence from the synthetic stock and lubricity from the mineral base stock. I think I can take care of you with a lil sump'n special.

drop me a PM with your address - I'll hook you up.

RickM · RickM's Garage

I use synth in my '85. No leakage.

kach22i · kach22i's Garage

Dino juice, it even smells better if it does leak.

mjshira · 05-03-2006, 02:52 PM

lubemaster77 (I felt dirty when I typed that) is right. On some older cars, seals, specifically the chain tension ones, 'sometimes' leak if you switch over to syn oil.

In my cars I run syn - no issues and longer life of oil.

kilodawg · kilodawg's Garage

Switched to Mobil one last change (97,000 miles). No leakage not one drop.

Navaros911 · 05-03-2006, 03:13 PM

Quote:

Originally posted by kilodawg
Switched to Mobil one last change (97,000 miles). No leakage not one drop.

On the 993, right

Just kidding...

I tried the Fina 5W40 full syn, but it started leaking like a siff; where it wasn't AT ALL when I bought it. So I just switched to mineral again, Mobil 1 Super M and it runs fine, less noise as well from the valves (just a side effect). It doesn't seem to leak anymore. I'll try half syn next time, but for now the mineral will do.

bmgmd · bmgmd's Garage

Have been alternating randomly for the past 5+ years. No leaks.

M.D. Holloway · 05-04-2006, 09:17 PM

Quote:

Originally posted by Navaros911
On the 993, right

Just kidding...

I tried the Fina 5W40 full syn, but it started leaking like a siff; ...

way to thin

dorschman · dorschman's Garage

I run LubroMoly 5w-40 synthetic in the 87 and leak about a drop per week (maybe less, hard to tell with a small amount). No increase since the switch about 4 months ago and have not had to add any oil yet.

real550A · real550A's Garage

I ran Mobil 1 15-50 in my '88 Carrera (as did the PO), with no leaks whatsoever.
I'm a big fan of high flow rates upon startup and lower temps.

Miguel Antonett · 05-05-2006, 04:44 AM

I used Mobil 1 15-50 in my 78-930. It leaks some - so what. I clean the floor once in a while. But have piece of mind with the turbo and cold starts. Why so concern about some minor leaks, it's part of the deal...

cnavarro · 05-05-2006, 04:58 AM

If you are already running Mobil 1 and you don't have any leaks or it barely marks its territory, why change? If anyone is interested, I did (and I am still doing) independent analysis of oils (additive packages, etc) and I have been posting the results on my web site. Some fuel for the fire :-) I have 30+ oils under my belt and have another 30 I'm waiting to send out for analysis.

http://www.lnengineering.com/oil.html

chuckr · 05-05-2006, 05:42 AM

I run Redline 20/50 in my 89 with NO problems....
I also ran Redline in my 83SC.... NO problems
Synthetics are the way to go. I have used Redline for
about 6 or 7 years, expensive but worth it IMHO.
Recently I've been reading about a Mobil One
oil for motorcycles called V-Twin oil. From what I
can tell, it is perfect for Porsches, I plan to switch
on the next oil change.... or whenever I get my new
car up and running, I'm swapping the motor out of my
89 that got totaled into an 88 that I just bought.
Chuck

wholberg · wholberg's Garage

I run Mobil 1 15W-50 in my 87 Carrera with no leaks at all. Have been running it for about 1 year (about 12K miles). The car has 101K on it right now.

cnavarro · 05-05-2006, 06:04 AM

I'm running Mobil 1 V-Twin 20w50 in my 70T and I run Royal Purple Max Cycle 20w50 in my 912 with the vintage race engine. The only observation I can make with the Mobil 1 is that your oil temps will go up, due to the added boron found in all their formulations which increases the oils ability to pull heat away from the engine. As long as you have sufficient oil cooling, that's not a problem. I also run Amsoil in my modern cars and have liked their V-Twin full synthetic formulation, so as you can see, I am very unbiased and not brand-centric.

Navaros911 · 05-05-2006, 05:18 PM

Quote:

Originally posted by LubeMaster77
way to thin

Ok, so in your opinion, should I stick to 10W-something and higher?

Also, is the Super M 'bad'? So it flows less at low temp, but it never gets that cold here.

Would the Mobil 1 Super S (only semi synthetic or a blend) 10W-40 be a good oil?

Thanks,
Michiel

drsimonwong · 05-05-2006, 05:41 PM

Mobil 1, 15w50 in my '85. Just changed from non synth 15w40 4000miles ago. No leaks to the floor but a "sweat" around the oil return tubes-but this was always there even before.

Some pretty hard running in that 4000miles with track days a regular event. Just topped up the oil last week. Only needed a quart.

My mechanic recommended the change as I've bumped up my track day outtings.

Simon