dannyboy

97 993 C4S

I'm reaching out for a little peace of mind , over the winter had some work done at my local indie , complete tune-up , clutch , wires etc...also a couple of seals one of which was the front crankshaft seal , soon realized that it was leaking and the indie at their expense changed the seal and also did an oil change and added a mineral non synthetic oil , their reasoning being a non synthetic oil is beneficial to seals & gaskets & often stops small oil leaks , as I've owned the car since new and have only used synthetic oil should I be concern. Many many oil threads and I've read them all & as far as I can see no one uses anything but synthetic...I've just purchased mobil1 Vtwin 20w50 but wondering if I'm overreacting..here is the oil installed.[img]cidF816B1D-145D-4D5E-9119-E7A3FB16AED8

LexVan

I'm not a believer in self correcting magic fluids for leaks.

Your selection of the V-Twin is an excellent one.

Just do an oil change in a few hundred miles.

HalfGerman

That old "advice" about synthetic causing leaks is due to the synth flowing better and seeping past brittle old seals ( sometimes cracked) more than conventional oil.That and the cleaning by the oil can remove varnish , build up on seals and poof you get OMG, synthetic caused a leak. But seeing how you have been using synth , I would think you would not have any build up from conventional oil use.

For a street car, I would just go back to synth with next oil change.

Churchill

It's no problem, just use v-twin at your next oil change in 3k-5k miles

pp000830

Synthetic oils in most cases are not made from a synthetic base they are just regular oil refined to a higher degree removing more components that the additive package needs to keep in solution to avoid sludge. The big advantage is that at cold-start where synthetic oil need not be as warm as regular multigrade oil to get into a viscosity range where its lubricating ability is effective. This is, in my opinion, the most important feature of oil labeled as synthetic. When your mechanic says regular oil help seal things up what he is saying is the oil forms sludge, probably mostly waxes that tend to plug things up. On the other hand, sludge interferes with oil getting oil in confined spaces in an engine so in my opinion his suggested benefit is outweighed by the downside. Mobil 1 is inexpensive at Walmart and when on sale, via rebate, it is downright cheap so there is no reason to not use oil labeled as synthetic.
Andy

Diego

Every vehicle I ever owned I switched to synthetic and have never experienced leaks or any other issues because of it, they didn’t leak before and they didn’t after the change. I have been changing the small o-ring every oil change, not sure if it’s necessary but I do anyway. Yes they are expensive, $12 Can. Our dealer doesn’t even have this o-ring in stock, I always have to order it so I order a few at a time. I’m sure the dealer doesn’t change this if they do an oil change on someone’s car because they never seem to have them in stock. Makes me wonder if it’s even necessary to change every time.

motobri

Wasn't there talk of the Porsche classic oil helping slow/stop small leaks/seeps?

notabot

Our cars will leak oil. It’s just due to the design and gravity. Only need to worry if it gets excessive.

Bill Verburg

Admittedly synthetic is more overkill than a necessity in n/a engines, It does flow better when cold and hold up better when overly hot but our engines especially in normal street use just aren't driven that hard and the oil temps are generally well controlled

for 993 original spec was different for syn and non
non
for normal summer use 15w-40,20w-50 or straight 40 w/ ZDDP 1100-1400ppm

syn
for normal summer use 10w-40, 15w-40, 15w-50 w/ ZDDP 1100-1400ppm

Both regular syn M1 and vtwin fit the bill

the only caveat is that the vtwin is formulated to accommodate wet clutches as used in most motorcycles, as such the friction modifier package is different, whether better or worse for our use I don't know

I do know that it's a lot more expensive and harder to get, so I just use M1 15w-50 in both of mine, going back 20-30 yrs or so

The canard about leaks is from the very early days of syn availability which was back in the 1940's for aircraft use, early examples lacked the components that would cause the automotive seals of the day to swell and thus seal. This issue was overcome w/ an additive package and hasn't been an issue for 40 years or so

JasonAndreas

Porsche has ALWAYS and for every model, specified a range of oil weights by ambient air temperature. The bearing clearance argument that I keep seeing regurgitated on RL has always been complete BS. The factory delivered every 993 with synthetic 5w40 until 1996 when they switched to 0w40. And prior to 5w40, the 964 was delivered with non-synthetic 10w30.

Bill Verburg

​​​​​​Read the owners manual, What I posted is right from mine

You are entitled to your opinion wrt to bearing clearance but most engine builders I talk to don't agree w/ your opinion

Please tell us the source for this yes, in the early 2000's the factory approved of 0w-40, but that was more a convenience for the dealers to not have to carry multiple different oils

yes, the 993RSRs, GT2evos and Cups were spec'd for M1 5w-40

964



993 owners manual