Severian

I've been using Valvoline Racing VR1 20W-50 conventional motor oil in my '89 944 for years because of its zinc content and never experienced any engine leaks.

I would like to try the Racing Synthetic VR1, but because of the high miles, about 150,000, I'm worried about oil leaking at the engine seals.

If I find that to be the case would going back to conventional oil resolve the issue or once the leaks start they're there for good?

To go synthetic or not synthetic, that is the question...

Humboldtgrin

If it starts leaks then it's probably just going to be a coincidence. At 150k your front sleeves are probably pretty groved from your seals and they may all need to be replaced regardless of what oil your using.

PaulD_944S2

If it leaks with synthetic, usually it will either stop eventually, or stop when you go back to dino oil.

harveyf

I use the synthetic oil exclusively in my track car. It doesn't have any leaks but it was fully rebuilt with new seals, etc. I am responding only to state that the VR1 full synthetic is somewhat harder to find for purchase. It used to be carried by one of the local stores but now I believe it one of those "off-road use only" type products, which causes the stores not to carry it. It can be had on-line. It runs $9 to $10 a quart.

Whether the seals will leak and whether you can "go back" is not a 944 specific question so you should be able to do a more general search and get some feedback that way.

Humboldtgrin

Synthetic oil has come a long way! The seals won't leak due to changing from synthetic to conventional oil. Or the other way around. Back in the day they had issues but not anymore.

Mongo

Anyone experienced catalytic converter failure with VR1? NAPA auto keeps frowning upon its use despite stocking it in my area.

bonus12

I would think that now or soon synthetic oil could be better than conventional considering you can design it just the way you want. Seems to be cheaper now, at least.

Humboldtgrin

I experienced a melted catylitic converter at 21 psi.

Severian

I wanted to find out for myself if I would experience any oils leaks if I switched to synthetics so my last oil change was with Valvoline Racing Synthetic VR 1.

It's been a few weeks since the oil chance, I've gone through a full tank of gas and over 300 miles of daily driving.

For what it's worth, I have not experienced any oils leaks what so ever.

And the oil level has not gone down at all, so I'm not burning any oil either.

BTW, my MPG went from 20.2MPG to 21.2MPG as a result.

I've concluded that if a high mileage 944 engine is in good condition, without any oil leaks on conventional oil, then there is little reason to worry about switching to synthetic oil.

I hope this helps someone out there wondering the same about their 944...

951Dreams

This is always one of those myth filled subjects, about as slippery (no pun intended, mostly) as the questions about what oil to use, what brand to use, etc etc etc.

I only own older cars. Mostly 20+ years old. I used 100% synthetic in everything I bought for several years, and all developed leaks after 6 months or so. Internet research, and a bunch arm chair engineering (guessing) seems to come to the conclusion that it's better at cleaning ( I can verify I got a lot of gunk out of the old engines the first couple of oil changes). And due to that, it can clean out gunk that was previously filling gaps from old shunk seals.

Now, there is a flip side to this. It could just as easily be that those that use Synthetic are more prone to change the oil like it supposed to be changed, and change filters like you're supposed to. The correct changes could in fact be what's doing the "cleaning", and the PO may have ran the old dino oil till it was tar again and again. Maybe many POs. My 38 year old GF didn't even know you were SUPPOSED to change oil in cars till like 4 years ago!!!!! No one had ever told her. She had owned cars since she was 18.

So my experience is that with older cars, it can cause or increase leaks. I'm 100% sure that depends on how well the car was taken care of before I got it. If the oil was changed right, and good oil was used, there should be no sludge, no crud, nothing for the synthetic to clean up and cause to start leaking.

In my cars, I've just started using GTX High Mileage. It's a conventional/synthetic mix, and even though they claim it helps to stop leaks with "magic" seal restorer, I find it also will start to cause leaking after about 3-4 oil changes. But after using it for years, and taking engines apart, some that were neglected before I got them, I can say it does a darn good job on the inside. Some I had apart before and after using it for awhile, 15k miles or more. And the difference was really astounding. Inside the engines looked new! No joke. But all leaked in the end.

I may have got the same results with conventional dino oil changed every 3k for 15k... I dunno. But with the 10 or so 20+ year older cars I've owned the last few years ( I go through cars like crazy) if they didn't leak, they started, using anything with any synthetic in it at all. And if they already leaked it got worse. (keep in mind, after 3-4 oil changes, not right away).

However, NONE of them ever had any friction related problems during my ownership...NONE. And all of the engines looked brand new if you got the covers off. Where before using it, they had gunk, grunge, sludge all over in many cases.

So, my .02 cents. My dedication to oil changes maybe the factor, not the oil. I can't say. But that's my experience. Also, now that I think of it I haven't used just straight conventional oil in anything for 15 years. So, I guess I have no control group really. But if memory serves, I had less leaking issues back then. Or now I just care more... dunno.

EDIT: Sorry, that got really long. Leaks or no leaks, use Synthetic or a mix. What it does for the insides is insane in my experience. It will clean up neglect also, but of course won't fix things that are already damaged. I have had it un-stick lifters however. But I'm a strong believer it will stop any damage that previous neglect started causing. So what if it leaks, that just means it's working ;P

black944 turbo

I to have had the experience of running synthetic and leaks starting. It took several thousand miles but they started. I have heard that synthetics have gotten a lot better about this though. I ran Mobil 1 back 13 years ago and now run vr1. Btw, once the leaks start changing back does not fix, but will slow them down.


I plan to switch back if I ever get to the point of resealing the entire engine.

CO951

I think there are too many factors to just blame it on the oil. I had a '94 4Runner with over 100k miles that I ran Castrol Syntec 5-50W in for more than 50k miles without a noticeable leak. Hell it even started fine many times after a night at -30*F (not wind chill). -40 was another story.
On the other had my daily driver '96 camry with over 200k miles has started leaking. I've put 50k miles on it with either synthetic or semi-synth oil. Is it the oil or the 250k miles?

951Dreams

I think it has more to do with how it was taken care of BEFORE the synthetic, than anything else. If it has fed good oil, changed every 3-5K, with a new filter, every time, then switching at 150k is not going to start leaks.

*start theory here* I THINK what happens is this: Gunk builds up on the inside around a place in a gasket (on a neglected engine). Gasket stops getting direct contact with oil and starts drying up and shrinking. That's fine, because the gunk is stopping it up. You pour in some of the GOOD stuff, and change it often, it goes to work getting everything cleaned up, like it should. I finally gets around to cleaning up that gunk that WAS sealing that small dried/shunk place in your gasket. Before the gasket can get rehydrated and swell it starts leaking. Once it starts, it never can really stop, wicking type action you see with fluids.

Sometimes the "seal magic" can do it's thing, and the leaks will stop, most of the time the "seal magic" stuff is useless and it just leaks, forever. But inside things are 10x better and your engine is happy, if your driveway is not.

black944 turbo

I will disagree on the neglected engine point. I have a ton of records for my car and can tell you without a shadow of doubt that my engine has always been well maintained and looked after. As far as the leak is concerned, it my have been coincidental, however during that time period I knew a lot of people personally that experienced the same thing on their cars.

951Dreams

Well, so much for that theory.... LOL it was just a theory.....

I do think synthetic is "thinner", and I have a whole other theory about using straight synthetic in older cars, especially older euro cars. But that wasn't the question, and it's just my theory.

So, it COULD find cracks other oil can't......

I guess.....