If you can stand another synthetic oil story
 

After my rebuild, and after the 500-mile break-in period, I put synthetic oil in my p-car.

There was a pool of oil leaking right under the crankcase and in a couple of other places.

I swapped it out and put in "real" oil, and the leaks are all gone.

- Bill

How did it taste? :)

oil question
 

What grade of Dino oil did you use? I just installed a used "rebuilt" motor and it is leaking the Synthetic out on my garage floor and the heat exchangers and I am considering switching back to Dino oil if that is okay for the engine. I just bought this engine and it apparently had Synethitic its entire rebuilt life.

BTW I didn't get the owners manual when I bought the car a month ago.

I use 20W/50.

I should add that it's Castrol GTX 20W/50 Dino oil. I'm sure you will be doing the car a favor to get rid of the synthetic oil. It seems to leak through the gaskets - at least it did for me.

I'm thinking of doing a blend. My seals have all "shrunk" from synth oil, but the overall leaks aren't bad. The blend gives you the benefit of the dino seal swell and the lube of the synth.

The overall quality of oil these days makes it a safe bet that any high level dino will be fine.

I haven't decided to go there yet, but I'm seriously considering it. The real upside is cost. Much cheaper to do dino... :)

This is a topic that goes round and round. I know that my mechanic told me to "Keep what the car is used to in it and when it is time for a rebuild we can transfer it over to synthetic ."

I am beginning to wonder if the seals that we get for our older P-cars are made from a different material than what is used for a newer, lets say "Synthetic Friendly" car.

Are the seals that we buy for a rebuild made of the same composition as the OEM's were? Is there a difference in the materials used in past than newer seals made since synthetic oils have been used in common practice?

Just curious. Anyone know?

I found that synth leaked in my 914 and 911, too.

I also found that my 914 went for well over 200,000 miles on dino oil, many of those miles on low tech straight weight oil in the early and mid 70s.

So, I have no problems just sticking with dino.

Did the same thing with my Carrera 3.0. Changed back to Dino and the leaks have subsided. Never would have believed it.

Alan Poh
'77 Carrera 3.0

Mobil 1 0W-40 on non-rebuilt motor and no leaks. Just your luck I guess.

I recently bought a well hamered 71 911t the previous owner was proud to tell it was runing on synth, I too have oil stains on the carpet in the garage, (well something has to soak it up). Any advice on what proper oil grade to use, I take it out in the sunshine 10-30 degC

Has anyone had a situation where going back to dino did not stop the leaks. That is, could synthetic oil create a leak which is permanent?

I have had a recent rebuild(1987) and am afraid of creating a permanent leak by going to synthetic.

I would use 20W50 or 15W50 - something in that range.

Anectdotally, the '88 3.2 in my car was rebuilt about 25k miles ago and the PO of the engine used Mobil 1 in it, so I have been doing the same (after years of being a die-hard dino oil user). I was under the car a week or two ago changing the gearbox oil and I was pleasantly surprised to see that the engine was dry and just about clean enough to eat off of...

Mike

Is it possible that maybe using a synthetic oil that doesn't contain detergents like mobil 1 would yield a non leaking engine that would still run on synthetic?

Mobil 1 0w40, 3.0 liter rebuilt, 8k since, no leaks.

Regards Gerko

I switched back to dino after a few thousand on my rebuild because it was leaking from the valve covers. My wrench suggested milling a fraction off the covers so the gasket will seal better (3.6 engines use a big O-ring type seal, not the flat seal). It leaks consistently near #1 and #6, but not #3 and #4

We learned this in meethigs with the Alfa Club from a guy whose company makes mil-spec synthetic oil:

Dino and synthetic use different seal-swelling additives. If your car is "used" to one kind stick with it until rebuild time. A Milano I used to have was burning Mobil 1 like crazy until I learned about the additives. I switched back to dino as the previous owner had used and oil use went down dramatically. However I am a strong Mobil1 advocate when you can use it from new. In my 1967 Duetto I still use Castrol 20-50 because it's an old style engine.

Ciao !

Dan
1967 Alfa Duetto Spider
1974 Alfa GTV ( 4-sale to buy 911 )

When I switched back from synthetic to dino, it stopped the leaks. I wasn't about to wait until the next rebuild, and I was tired of oil on the floor.