The oil selection is seen as a religion, especially with regard to brands, but ultimately it is about the engine itself and the various viscosities that are available
The agony of choice
First of all, any engine oil from 5w40 up to 10w60 with API approvals from SE or SF as well as the manufacturer’s approvals, such as VW, MB and of course Porsche A40, can be used for regular 2.7, 3.0 and 3.2 engines for the road and in factory condition – it just depends on the area of use.
98% of all owners of classic 911s drive their engines on rides or other occasions with normal stress, i.e. far away from what is required of the oil on the race track, and it is this normal stress that I am referring to here. In the table below are values from the manufacturer data sheets of the various multigrade oils. If one compares here the versch. Viscosity classes with each other, it quickly becomes clear where the differences really are.
https://de.oelcheck.com/wiki/Viskosit%C3%A4t
https://de.oelcheck.com/wiki/VI_%E2%80%93_Der_Viskosit%C3%A4tsindex
The viscosity index can be calculated online using the corresponding mm²/s values below (at 40°C and at 100°C), therefore not listed below:
http://www.nimac.de/viscosity-calculators/viscosity-index-kinematic-viscosity
However, the viscosity does not increase linearly with increasingly colder temperatures:
Kinematic viscosity (red) in the temperature curve for a 15w40 oil – Source: wiki.anton-paar.com
If you want to calculate the respective values for e.g. 10° , 0° or -10° C, you can do this with this online calculator:
https://wiki.anton-paar.com/de-de/astm-d341-extrapolation-viskositaet-temperatur/
Viscosities in mm²/s at given temperatures of exemplary oils of various brands with different SAE classes:
| Sort of Oil | Visc.Index | 100° | 80° | 60° | 40° | 25° | 0° | -10° |
|---|---|---|---|---|---|---|---|---|
| 20w50 mineral | 121 | 18 | 32 | 65 | 164 | 390 | 2663 | 7034 |
| 15w50 vollsynth | 164 | 18 | 30 | 56 | 123 | 253 | 1200 | 2642 |
| 15w40 mineral | 136 | 15 | 24 | 48 | 110 | 240 | 1340 | 3254 |
| 10w40 mineral | 150 | 14 | 23 | 44 | 96 | 201 | 1008 | 2307 |
| 10w60 vollsynth | 178 | 23 | 38 | 71 | 153 | 310 | 1404 | 2998 |
| 5w40 HC-Synth | 169 | 14 | 23 | 42 | 88 | 176 | 800 | 1728 |
| 5w40 vollsyth | 172 | 14 | 23 | 41 | 85 | 376 | 715 | 1498 |
| 5w50 vollsyth | 186 | 18 | 29 | 52 | 107 | 207 | 848 | 1720 |
| 0w50 vollsynth | 189 | 17 | 28 | 49 | 100 | 192 | 771 | 1551 |
If the car is started and driven also in mild winter days and thus at cold temperatures, one should perhaps not necessarily fall back to a 20w50, but rather a 5w40 with entspr. release drive.
Viscosities in mm²/s at temperatures of 40°C and 100°C of exemplary oils and brands:
| 5w40 Oils & viscosities | mm²/s / 40°C | mm²/s / 100°C | API & Release |
|---|---|---|---|
| CASTROL GTX 5w40 | 78,0 | 13,2 | SN |
| Mannol Extreme 5w40 | 79,2 | 13,3 | SN / A40 |
| Liqui Moly LL High Tech 5W-40 | 80,5 | 14,0 | SN/ A40 |
| Meguin High Cond. 5W-40 | 80,5 | 14,0 | SN / A40 |
| Motul 6100 Synergie 5w-40 | 85,3 | 14,1 | SN |
| Mobil Super 3000 X1 5W-40 | 84 | 14,1 | SN / A40 |
| CASTROL Edge 5W-40 vollsyn. | 75,0 | 13,0 | SN |
| Mannol Elite 5W-40 vollsyn. | 80,5 | 13,5 | SN / A40 |
| Liqui Moly HT. 5W-40 vollsyn. | 90,2 | 14,5 | SM / A40 |
| Meguin 5W-40 vollsyn. | 90,2 | 14,5 | SM / A40 |
| Motul 8100 5w-40 vollsyn. | 84,7 | 14,1 | SN / A40 |
| 15w40 Oils & viscosities | mm²/s / 40°C | mm²/s / 100°C | API & Release |
|---|---|---|---|
| Castrol GTX 15W-40 | 102 | 14,3 | SL |
| Mannol Universal 15W-40 | 105 | 13,9 | SG |
| Liqui M. Touring HT 15W-40 | 101 | 14,4 | SL |
| Meguin HD-C3 SAE 15W-40 | 101 | 14,4 | SL |
| Motul 4000 15w-40 | 110 | 14,6 | SL |
| Mobil Super 1000 X1 15W-40 | 107 | 14,4 | SL |
| 5w50 Oils & viscosities | mm²/s / 40°C | mm²/s / 100°C | API & Release |
|---|---|---|---|
| CASTROL Edge 5w50 vollsyn. | 109,7 | 17,87 | SN |
| Mannol 5w50 HC-Synth. | 99,1 | 16,6 | SN |
| Liqui Moly 5W-50 vollsyn. | 117 | 18,5 | SJ |
| Meguin SuperLL 5w50 vollsyn. | 122 | 18,7 | SM |
| Motul SPORT 5w50 vollsyn. | 107,1 | 17,9 | SM |
| Mobil 1 FS x1 5W-50 vollsyn. | 101 | k.a. | SN / A40 |
| 20w50 Oils & viscosities | mm²/s / 40°C | mm²/s / 100°C | API & Release |
|---|---|---|---|
| Castrol Classic XL 20W-50 | 153 | 17,3 | SF |
| Mannol Safari 20W-50 | 158 | 18 | SL |
| Liqui Moly Touring HT 20W-50 | 153 | 18,1 | SL |
| Meguin Universal SAE 20W-50 | 153 | 18,1 | SL |
| Motul CLASSIC 20W-50 | 164 | 18 | SF |
| Mobil Super 1000 20W-50 | 146 | 17,8 | SL |
| 10w60 Oils & viscosities | mm²/s / 40°C | mm²/s / 100°C | API & Release |
|---|---|---|---|
| Castro Edge Synth 10w60 | 160 | 22,7 | SN |
| Mannol 10w60 | 165 | 22,3 | SN |
| Liqui Moly Syn 10w60 | 168 | 24 | SL |
| Meguin Racer 10w60 | 168 | 24 | SL |
| Motul 8100 X-POWER 10W-60 | 163,4 | 23,5 | SN |
| Mobil 1 Extend. Life 10W-60 | 152,7 | 22,7 | SN |
What can also be seen above is that the special „Classic“ engine oils come with an API SF. This identifier applied in particular to engine oils of the 80s.
https://de.wikipedia.org/wiki/Schmier%C3%B6l#API-Spezifikation
https://www.usteile.ch/blog/oldtimer-und-muscle-cars-motoroele-mit-zddp-additiv/
In addition, these API SF oils usually have a higher ZDDP content of up to 1,400 ppm, which has a wear-reducing effect and was reduced to as low as 600-800 ppm from the 1990s due to catalyst properties/compatibility.
https://www.fomoco.eu/technische-informationen-f20/zddp-motorenoel-additiv-t517.html
However, there are also oils with modern API, which still have a higher ZDDP anneil and still come with a cat release.
Modern oils with higher API classifications and still high ZDDP content are e.g:
• Liqui Moly 20w50 Touring High Tech
• Meguin 20w50 Universal (1:1 wie das o.g. Liqui Moly, da Meguin zu Liqui Moly gehört)
• Liqui Moly Synthoil High Tech 5W-40 (vollsynthetisch)
And of course products from many other manufacturers and here possibly to read:
https://oil-club.de/index.php?board/2-frisch%C3%B6l-f%C3%B6a-voa/
Personally, I also like to drive the 11 on cooler days, when the sun is shining, there is no road salt on the roads and the outside temperature does not drop below about 10° to 7 °C. Here, it is generally good if the oil is thin enough to quickly reach all lubricating points. Here, it’s generally good if the oil is thin enough to quickly get to all the places that need lubrication.
I had the engine open last year, and in the course of that had everything completely sealed, and filled up with a mineral 10w40, and have now gone back to 15w40 when changing the oil again. Oil pressure is wonderful across all temperatures and RPMs and even after a long time everything is completely dry underneath. Even a 5w40 wouldn’t really be a problem here because the common 5w40 oils, even the ones from the hardware store, have a Porsche A40-compliant release. Many authorized Porsche dealers fill 3.0 and 3.2 engines with 5w40 as well as their own 10w60.
I can recommend the following two engine oils with the best price-performance ratio in terms of an optimum ZDDP content, which are also recommended by the oil manufacturer for older vehicles up to the end of the 80s:
LIQUI MOLY Formula Super 15W-40
LIQUI MOLY Touring High Tech 20W-50
Both oils have a ZDDP content of about 1,200 ppm, making them ideal for 911 engines in the 2.7, 3.0 and 3.2 models. The following threads on this:
https://forum-liqui-moly.de/index.php/forum/motoroele/1580-zddp-anteil-lm-1440-formula-super-15w-40
https://forum-liqui-moly.de/index.php/forum/motoroele/209-motoroel-fuer-oldtimer-v8
Previously, however, I had referred to the above-mentioned products to those alternatives of the brand Meguin, because it is the manufacturer of the oils of Liqui Moly and belongs to that brand, so 1:1 contains the same oils. However, Meguin has raised the prices in the meantime to such an extent that it does not matter whether you fill Liqui Moly or the 1:1 equivalent of Meguin. I would like to point out that I have no relationship with either company or receive any benefits from this article.
In general, as far as „brands“ are concerned, here you can also fall back on other oils from the DIY store or on offers from reputable mail-order companies with an assured origin without any problems, as long as the above-mentioned approvals exist. Much more important than the choice of a premium oil brand is the timely oil change. Since we pay here for the required 10 liters less than 50€, an annual oil change is a ritual, which should actually be self-evident.
How often do you read in forums that for many drivers the brand names represent a true religion, but what good is an expensive brand oil with a, for the intended use suboptimal viscosity, and on the other hand I leave it too long in it and also drive a too rich mixture over all load conditions. Then, at the latest during the oil change, you can smell how the used oil smells of gasoline, which is above average. In the end, this cancels out any alleged brand advantage of the oil – if it exists – by then at the latest.
I would recommend for a newly revised and resealed 3.0 engine a 5w40, 15w40 or generally a 20w50 as standard, with higher ZDDP content, and if only summer driving and the engine already has many km on the hump, a 20w50 is then also a good choice.
Oil change done by yourself
You can change the oil yourself without any problems. In addition to the 10 liters of oil, a drain pan is also necessary. A 7-liter version is particularly suitable here, since the oil tank and the crankcase are emptied separately anyway and the 5 liters can be easily filled into two old 5-liter canisters from the last oil change.
If the change is carried out in the summer when the oil is hot and the car is tilted slightly backwards, it may happen that the thermostat in the right rear wheel arch is still open due to the temperature and the oil may drain out of the lines that go to the front oil cooler to the rear when draining. In this case, more oil must be added at the end.
It goes without saying that the filter should always be changed as well. The oil is drained from under the crankcase by loosening the large screw on the oil strainer cover (see illustration above) and, after draining and reinserting the screw together with the new aluminum sealing ring, by loosening the screw at the bottom of the oil tank in the right wheel housing. Finally, the two old 5-L canisters filled with used oil can then be returned free of charge, e.g. at Obi or similar. It is important that a filling up of the oil, this does not happen up to the max. mark on the dipstick. Here the middle between min. and max. is exactly correct, in order to reduce later the possibility of an arising smoke cloud with the cold start, as described further down.
The used oil can either be taken to the supplier from whom the oil was purchased, or – if purchased online – then to a recycling center in the vicinity, or – if no oils are accepted there – e.g. to a Construction market where here in germany they do accept used oils.
The typical boxer fart –
blue smoke at cold start
Blue smoke is caused by an excessively high oil level in the engine during a cold start. If the car is also standing on an inclined surface, the smoke is pre-programmed when starting.
The rule here is not to continue filling the oil beyond the midpoint between min and max. Even at min. there is still perfectly adequate lubrication.
White smoke, on the other hand, is perfectly normal after a long period of standing and disappears by itself after some time of driving. This is condensation in the exhaust system, which forms when the vehicle is parked for a long time in the garage or similar and ambient temperature fluctuations occur.
Black/gray smoke, on the other hand, indicates a mixture that is much too rich, or that there is unclean or incomplete combustion in one or more cylinders.
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The names Porsche, 911 and 911 SC are registered names of Dr. Ing. h.c. F. Porsche AG
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