This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.
One of the most common tasks to perform is the replacement of your engine oil. Frequent oil changes are supposedly the most important thing that you can do to maintain and prolong the life of your engine. With the better oils that are available today, the requirement for frequent changes is diminishing. Even though Porsche now recommends oil changes every 15,000 miles or so, it's usually recommended to keep the changes under the 5000 mile limit. If you don't drive your car too often, then the changing of the oil should be done at least once a year to keep things fresh.
The first thing you need to do is to make sure that you have everything that is required for the job. Nothing is more frustrating than emptying your oil, only to find out that you don't have a replacement filter, or not enough oil. You will need an oil filter, a wrench, a roll of paper towels, a very large oil pan or bucket, and about 12 quarts of oil. Check the bottom of your oil tank for the appropriate sized wrench that you need: it's not uncommon for the older cars to have different sized drain plugs than were originally installed. Start by driving the car around, and letting it heat up to operating temperature. You want to empty your oil when it's hot, because the heat makes the oil flow a lot easier, and more particles of metal and dirt will come out when the oil is emptied.
Once you get the car parked, place the oil pan bucket underneath the oil tank of the car. The 911 uses a dry-sump system which holds the majority of the oil in the oil tank instead of at the bottom of the engine. There is still plenty of oil at the bottom of the engine, but there isn't enough for the engine to run properly, so the oil tank holds the reserve. The oil tank for all 911s (except 1972) is located on the right side of the car, inside the rear fender just behind the wheel. At the bottom of the tank there is a plug that is used for draining oil. Remove this plug carefully, and make sure that you have a very large oil pan underneath. The oil pan should be capable of holding about nine quarts of oil. Place a drip pan underneath in case you underestimate. The oil will be very hot, and will empty out extremely quickly, so be careful not to burn yourself. There will be no time to grab any more buckets or oil pans, so make sure that the one you choose is big enough.
Now is a good time to remove the oil filter. You want to make sure that you remove the filter with the oil pan still underneath the oil tank because the oil filter is full of oil, and this oil will have a tendency to drip down out of the filter into the tank and out the drain hole. The filter should only be on finger tight, but you may need a filter wrench to remove it. If the filter is really on tight, you may need to resort to more drastic measures. One sure-fired way to get the oil filter off is to poke a hole in one side of it and out the other with a long screwdriver. Using the handle of the screwdriver gives you the leverage that you need to remove the filter. It doesn't matter that you are destroying the filter, because you are going to be installing a new one. Be aware though, that this method will leak oil out of the filter into your engine compartment, so have some paper towels handy.
After the oil tank is empty, proceed to the center of the bottom of the engine, where you will find a similar plug on the bottom of the engine. In a similar manner to the oil tank, remove this plug, and empty the oil into your oil pan. The bottom of the engine sump will contain significantly less oil than in the oil in the tank. Starting in late 1983, Porsche moved the location of this drain plug from the bottom of the engine to the side of the case.
While all of your oil is draining, take the two plugs from the engine and the tank, and carefully clean them with a paper towel. The plug at the bottom of the engine is magnetic, and attracts all the little bits and pieces of metal that get trapped in the engine oil. Sometimes the plug on the bottom of the oil tank is magnetic as well, depending upon whether it has been previously replaced. When both plugs are clean, replace them in the car and make sure that you install new metal gaskets around the plugs. If you don't use the gasket, they will leak oil. Torque the two plugs to spec.
Now head back into the engine compartment, and install the new oil filter. Install the oil filter with the seal wet: wipe a small bit of oil on a paper towel, and use it to make sure there is oil on the seal all the way around the filter. Screw on the filter and make it snug tight. No need to use the iron grip of death when tightening the oil filter: these don't have a tendency to leak.
Now it's time to fill up your 911 with motor oil. A lot of people aren't really sure what motor oil to use in their car. Traditionally, the characteristics of motor oil were linked closely to their weight. Heavier weight oils protect well against heat. Lighter weight oils flow better in engines in cold environments. In general, if you live in a cold climate, you should use a 10W-40 or similar oil. This oil is a 10 weight oil that behaves and protects against heat like a 40 weight oil. In warmer climates, you should use a 20W-50 oil. This oil doesn't flow as well at the colder climates, but gives an extra âedge' on the hotter end.
The question of whether to use synthetic or âdinosaur' oil often comes up amongst car buffs. Consumer Reports (July 1996) did an extensive test a few years ago on both types of oil, and after tearing apart engines, and measuring wear, they couldn't find any discernable differences between the two. Still some people swear by synthetic oil. In general, you should not use the synthetic oil if you have an older car with old seals in the engine. There have been many documented cases where the addition of synthetic oil has caused an otherwise dry car to start leaking. If you own an older 911 that doesn't have fresh seals in the engine, I would stick to the non-synthetics.
Fill your oil tank from the oil filler neck in the engine compartment. I recommend removing the oil dipstick so that you don't pour oil all over the end that you need to hold. Add about eight quarts to the oil tank, and add an extra quart if you have a 1973 and later 911. Put the dip stick back in, and the oil cap back on.
Now, take the car out for a drive and bring it up to operating temperature. The oil level can only be checked with the engine running at idle and at operating temperature. If the oil level is low, then add more oil while the engine is running. One to two quarts of oil added to the tank will make the oil level on the dipstick rise from the low mark to the high mark. One rule of thumb is to fill the oil tank until the dashboard gauge reads just above it's half-way point. Make sure that you double-check the dipstick when you are finished. If you add too much oil, then the oil will eventually find it's way into the breather hoses, and could make a mess of your engine compartment. Make sure that you dispose of your old oil at a respectable recycling station.
On all 911s, the oil filter is attached to the oil tank. Be sure to arm yourself with paper towels, as it is almost impossible to avoid spilling at least some oil when removing the filter. The oil tanks on all 911s are located in the rear of the car inside the right rear fender, except for 1972 cars, when they were located towards the front of the car. The oil filler neck is also shown in this photo. The dipstick for measuring oil level is contained in a slot inside the filler neck.
Make sure that you plan to have a very large container below the oil tank. Approximately 4-6 quarts of oil or more will empty out of the tank very quickly. It's also wise to have a drip pan underneath your container. It's very easy to underestimate the amount of oil that will empty out of the tank.
Approximately three to four quarts of oil will empty out of the bottom of the engine. Although not necessary during each oil change, removal and cleaning of the sump screen on 1965-83 911s can help keep your engine oil cleaner. Remove the eight nuts that hold the sump plate on and clean the screen carefully. If you notice bits and pieces of metal or other debris in the screen, it may be a sign that it's time for you to rebuild your engine. Make sure that when you reinstall the screen, don't place the drain plug under the oil pickup tube: it can interfere with the oil pickup and circulation.