Porsche Classic 10W-50 Oil Change Interval?

[OK-944]

I’ve driven just over 3,200 miles (appx. 100 miles/week) since last March 17th - the date that I added a fresh fill of the Porsche Classic 10W-50 brew specifically formulated for our water-pumping P-cars. Porsche touts this oil as having exemplary flow characteristics, great keeping qualities, and relatively low amounts of acidification during those intervals when a car may sit idle.

My 87NA, by the way, loves this oil…and I’ve only noted about 1/16th inch loss on the oil stick during this entire 3.2K interval, while the color on the stick has remained a healthy looking amber. While I would expect that my recently rebuilt and properly broken in engine would exhibit only minimal oil consumption over time, especially given my relatively “conservative” driving habits (always holding back to let things warm up, and rarely revving higher than 4K rpm’s)…I’m still more than pleased with the actual results, and am now considering foregoing my usual fall oil change in favor of leaving things alone until next March - meaning an oil change interval of 1 year.

I will continue to drive my car through the winter…about half as much as during the warmer months, but still enough on each drive (as always) to get everything (engine/drivetrain) properly warmed up. With this in mind, I would anticipate adding somewhere between 1 and 1.5 K miles, meaning a roughly 4.5 to 5K total distance per one year interval between oil changes.

My other thought about driving through the winter before my next oil change is that, even when considering all of the above, I’m thinking it likely that over the past seven months/3 K plus miles of driving with this (Porsche Classic) oil, it has likely sheared at least enough so that it is now just a tad thinner and perhaps better suited to our cold winter temps. than it would have been fresh. Does this make sense?

[Monkey Wrench]

all oils need to meet certain ISO standards. Even if the oil has the name of your favorite grocery store as the brand name, its made to the required standards by the oil companies. they label to suit the customer, a grocery store does not make oil.

My personal take on the issue is there is so much advertising ,and often it's based upon some theoretical explanation which you as an end user can't analyze, or deny , prove or disprove. Its just marketing!

my take is change your oil, use the right weight and any brand, better to put your money towards more frequent oil changes than buy better oil... there is a lot of wordy marketing out there to encourage you sway your judgement. Ill pick one that's the middle of the road, not necessarily the cheapest or recycled, but Brand X is on sale, fine. I'll never taste the difference ;-)

I like to date my filter with a big black marker. It also doesn't hurt in a case like yours to change the oil and leave the filter alone as long as you do change the filter regularly. If it got clogged it could restrict flow. in an extreme case it might bypass the filter. I doubt that's the case with your filter right now from what you said.

one thing I'll often do which some may or may not recommend is to drain my oil, then crank it over a little or even start it just momentarily..like 3 or 4 seconds only.. the bearings are all still wet I dont run it long or anything . It empties the filter into the pan, or at least most of it.. then when i take it off I spill less on myself and all around me, since it's not completely full.. I dont think it harms anything, others may not agree. It won't be suggested in a manual to do that.

some swear by synthetic.. I'd just say change your oil, and your frequency sounds fine..

Filters.. I've been told many times that the Volvo oil filter , which cross references to a Fram one PH43 if I remember right.. is different. the difference is that one filter has a valve that prevents the oil from draining back into the pan during shutdown, the theory from what Ive been told is that the engine starts and takes a bit longer to build pressure. I dont think all the oil drains out of the filter but there may be some differences in the way it's constructed or it's internal valving.

If you see cutaways of different filters you can see big differences in the material used and the arrangement so they are not all the same. I try to stick to a name brand, Volvo, Mann, Bosche etc..

car companies dont make filters or oil. My take is that it's just rebranded if it has an auto makers name on it. If you buy enough oil or filters they will print what you want on them.. Marketing...

[TibetanT]

OK-944:

I would recommend 10W-30 or 10W-40 for Winter use of the 944. IMHO, these weighted oils do a better job for cold weather use.

Personally, I have always used 15W-50 Mobil 1 Synthetic in both my 1987 944S and 1983 911SC during hot weather and then, change over to 10W-30 or 10W-40 Mobil 1 Synthetic oil in Winter. (I do not drive the cars during Winter because of salt and other corrosives that are put on the roads).

I do this in Winter months to ensure they are ready in an emergency situation where the car must be moved out of the garage. I know this seems somewhat wasteful it does make for a better startup in the Spring, while temps are still cooler, for drives before Mother Nature turns up the temperature. Also, it does help with storage so nothing internal gets fussy. I do have my reasons for always using Mobil 1 Synthetic, and it does do a better job of keeping seals "healthy" within the engine compartment.

Just my .02 cents

Hope this helps,

Ed

[djnolan]

send a sample to Blackstone Laboratories for oil analysis. Most likely they will tell you it has plenty of viscosity and doesn't need to be changed yet. They will also check for contaminates indicating any other problems.

[walfreyydo]

This question comes up alot and the answer is easy - its all in the owners manual... Not running the correct viscosity for the current outside temperature can cause bearing wear. Modern engines can get away with lower viscosity because they have tighter tolerances. Dont make the mistake of thinking that you can run 0W oil in your 80s era 944 because thats the oil your wife runs in her 2020 honda. I see that thinking a lot especially on the facebook groups.



All that said, 10W-30/40/50 would all be good choices for winter - depending on how cold it gets in your part of the world/country

[OK-944]

I like the idea of sending off a sample of my current oil for testing...and depending on the results of this I'll either leave this oil in until next spring, or maybe go with a 5W-40 until then (knowing that I'll be driving this car at least twice per week over the cold, Vermont winter), and changing back to the Porsche 10 W-50 formulation when the weather warms up a bit.

[Monkey Wrench]

sample testing might be more expensive than new oil unless someone does it as a free service?

i was just speaking with a hydraulics tech and asked that question about a tank of fluid and he said new oil is cheaper, It takes about 30 gallons of hydraulic fluid.

two such people have told me that hydraulic oil is dated and expires. some of the machinery i work on sits most of the time so he said change it for the reason of age. I never thought a closed up oil container would expire. he said the additives have a shelf life.. Hard to argue or dispute that. I dont know.

[djnolan]

The report may or not be worth the money but there is a lot of details

https://www.blackstone-labs.com/engine-types/gasoline/#

[Monkey Wrench]

True that the learning has value and might give on a better perception to make such choices. that goes beyond the dollar value.

what i do sometimes is put some sea foam in the oil. run it a day or a week and then do the oilchange. it removes a lot of sludge from parts. I don't know if it's necessary if you do your oil changes regularly. I'll do it if I buy an old car that I feel has had poor service and Id also do it on an older engine if I was going to rebuild it just so its cleaner inside to work on. My brother fixed Harleys for a living so he had engines apart often and he seemed to think it was really good for that.

ill spray the spray cans odf sea foam into the intake sometimes or put some in the gas occasionally.. especially if the engine is old and a bit tired..

I dont know if it has any issues like swelling rubber parts. Its hard to tell sometimes. maybe others have opinions on it's use or what is overuse of it.
too much of a "good thing" isn't always good either.

I started wondering if it might be ok to pre-charge a new fuel filter by filling the filter and then installing it. then it would go through the injectors and might help clear them?

many cars have a air mass meter and I don't think it is good for that as they say to spray it in after the mass meter, but my Porsche has a barn door type sensor not a mass meter (I think) so maybe after the air filter is ok?

I usually just run 10W-30 or maybe 20W-50 in an old and tired engine, my thinking is bearing clearances are bigger with higher mileage. I have not paid a lot of attention to time of year.. I tend to change it when I feel like doing it and maybe if the dipstick looks dark. I dont track the mileage but usually I'll just know the last time I did it and I like to mark the filter so I can refer to that. Ive never been too scientific about it but if it looks dark Ill change it.. In my old volvo 122S I do it a bit more because I tend to rev it up and drive it really hard when I do use it and it doesn't get driven a lot. my daily use cars I just roll along like I'm getting paid hourly for my driving.. gas is expensive so that's a motivator to take it easy ;-)
a little off topic but
here's what my Volvo 122 looks like ;-) an original ad..

they were originally named the "amazon" but that interfered with a trademark for a bicycle manufacturer so they are still often referred to as an "Amazon" mine is in fact built in Canada so it's called a Volvo Canadian.
Volvo was originally a bearing company and Volvo means "I roll"

https://www.youtube.com/watch?v=y1qLDbR27fs&ab_channel=stockelbo

I love the thing, its so simple and robust and Ive driven it like that lots and they hold together so they were formidable rally cars back when they were current. It had 120 HP new and quite a bit more now after some tweaks.. it wasnt; that far behind the porsche in power considering it's 20 years earlier.. Wee bit more body roll though ;-) straight axle, they pick a certain "atittude" with the body roll, and then drift through a corner whereas the Porsch 944 will stick a lot better. Still fun ;-)

skinny little tires.. same as an old VW bug

"cheaper than Psychiatry" they say at the end,, fun advertising..

[OK-944]

My thought about having my oil tested has nothing to do with determining if I should change it (although this would be a bonus extra)...but more to test the efficacy of my recent rebuild. Make sense?

[Monkey Wrench]

makes sense if you do it a few times and can draw comparisons. I don't know if I'd personally have the smarts to diagnose by looking at the results myself, some would.