Porsche Enthusiasts Club Forum

In the UK typically a 10/40 personally I run a good quality mineral & change it every 3k, you could run synthetic or semi synth but if you change it every 3k it's then wasted. Official oil change intervals are 12K but a lot depends on how many miles a year you do & how many cold starts.
A semi synth might be better if you do track days or trips to Germany where it stays at high speed longer.

I've just switched to using 10w-40 magnatec in my lux and I think it's an improvement over the fuchs semi-synth that I was getting from GSF beforehand. I change mine every 6kmiles religiously, but I think a 3k interval would be overkill unless your car's a track slag.

Adam

Magnatec is good marketing but OK as a plain mineral oil. Mine only does 2K a year these days so it becomes an oil change a year. That's why I made the comment about whether it's a daily driver or not, also whether it's short journeys or long. I've always used basic oil in non-turbo motors & changed it often.

we use duckhams 20/50 mineral oil in all performance cars. its cheap as duckhams was and possibly the best.

If you keep your car in a garage 20/50 is fine. In mine (Outside & used most days.) In winter the oil was too viscous. It blew out gaskets regularly. Switched to Fuchs 5/40 & it was much easier to turn over & warms up faster. Consumption may be an issue with lighter oil if your engine isn't fresh.

I wouldn't use 20/50, I have 10/40 Mobil Super in the S2 at the moment.

I use Castrol RS 0w40 fully synthetic in my S2 and Castrol Edge 0w40 fully synthetic in my 924S with no problems. Both start well do not use any oil (more than expected) and do not blow it out through the air box or crank breather. I used to run Magnetec 15w40 semi synthetic in my 924S and it was much noisier at start up and tended to blow a small amount out of the crank breather.

The S2 runs much quieter on start up with the thinner synthetic oil probably due to easier flow to the lifters.

I also noticed both cars have much more stable oil pressures not any higher just more stable even after a long fast run the S2 reads around 5bar above tick over and around 2.5/3.5 below 1500rpm. I change my oil every 6 months including filter and it might work out a bit expensive but in my mind worth it but everyone to their own I suppose.

never had problems with high performance mitsu engines all of which are turbo'd and i believe they rev 1000 rpm higher than porsche too.

its like the same old argument with mitsu owners that swear you can't use anything but 0/40 mobil1 because any other oil with knacker the engine....nah this country is too cold for thin oils most cars we deal with or have are pre '95 cars giving them a grand old age and a lot of engine mileage and wear. and lets be fair oils have come a long way since regular hypergrade stuff. 20w/50 is fine for most uses especially in the summer but its also beneficial in the winter too

agree, may find a difference in indicated oil pressure dependant on oil type or grade, obviously thicker oils will have a higher indicated pressure and the engine will probably use less, under load and above 1500 rpm it should show near enough 5 bar regardless of the oil, its tickover when fully warmed that it will drop, i think above 2 bar shows a healthy engine

its all down to the tiredness of the oil pump and how worn the engine is at the end of the day. a fresh built or new engine could happily run 0 grade oil

If your going to want your engine oil changed and then forget about it for 12000 miles and 12 months, have an average mileage (probably 100,000 to 200,000) on the clock and want to be able to do track days, drive it however you want and not worry, I would recommend using something like Mobil 1 Motorsport 15w50

Its expensive, really expensive, I agree.

If you change your own oil, a semi synthetic 10w40 would be ok as long as you change it often (6000 miles or 6 months) Your time is free, so you can afford to change it more often.

If you pay someone to change your oil, it may be worth weighing up the costs and have a decent oil put in there right from the word go and leave it in there for 12 months and 12000 miles.

Its just my opinion and thats all it is, based on experience... You can put crisp'n'dry in as oil if you want and I bet the engine will not blow up right away... but it will

Quite agree Jon, my car is doing less than 3k a year so I feel mineral oil changed every 3K or once a year isan ideal solution. In non turbo motors it's still higher spec than when it was designed.

I think 20-40 may be a bit tooo thick for the 944 with it's big lazy-revving 4-pot though? And I thought that a thicker oil (at cold) would afford the engine less protection at startup i.e. when the majority of wear is supposed to occur?

Adam

In the temperate UK 20/50 is OK, the bar chart in the manual covers 10/40 to 20/50 in typical UK temps. Mine is on 15/50W Valvoline Turbo which I buy in bulk at around £12 per 5 litres, it's very high spec, SL I think which will be 3-4 levels higher than when it was new.
If you live in the dark wastes of the North then it's quite possible that you need to be on 10/40W rather than 20/50.

The whole point of synthetic is extended oil change intervals, as well as increased protection for very high temps applications such as turbos. Most semi-synths are no better than mineral oils, if you don't believe me check the specs on the can.

Personally I would avoid full synthetic oils. I ran Motul full synthetic in my Honda 4 stroke racing engines for a season. I found that it glazed the bores extremely quickly and the performance dropped of during endurance, resulting in an increase in maintenance. Switching back to a good quality mineral oil made a considerable difference and reduced maintenance.