Article reproduced with the kind permission of Mike Fishwick

Many new owners seek advice about which oil to use for their BMW, and the best advice is to be found in the Owner’s Handbook, which has a couple of pages regarding engine oil – but it is unfortunately commonplace for previous owners to retain the handbook. These little books contain a lot of other useful information, and are well worth buying. For those who are loath to spend money, or whose eyes can only read text from a screen (young males!) searching the internet will discover online copies in .pdf format.

As an example, here is a copy of the oil chart from my 2.8 handbook, which covers the 1.9 litre M44, 2.8 litre M52 series, and S52 M3 engines. These oils are also suitable for use on most of the later engines, but always check in your handbook, for some, such as the S54 M3 engine have different requirements.

As you will see, this gives quite a choice of mineral oils for a 1.9, but the better choice is a fully synthetic (‘Special’) oil of SAE 0- or 5- Winter viscosity, such as a 0-30 or 5-40 grade. The API approval level (which is more important, as it covers other factors than just viscosity) specified is SH or CD/CE, which were the ‘best’ approval ratings of 1998. SH was for petrol engines, and CD/CE for diesel engines, these oils having a bit more detergent content to keep the engine clean, but are equally good.

Things change, and SG oils are now thin on the ground, the current API approval having now progressed to SJ, which has less tungsten and zinc additives in order to extend the life of the catalytic converter. These heavy metals were used as a ‘fall back’ or boundary lubricant to reduce wear during cold starts when the lubricant film may have drained away from areas such as cams and followers, but modern SJ oils are so good that its absence is not an issue in anything but a ‘Classic’ engine.

On the choice of oil, I would use a synthetic even for an M44 engine, as these use roller cam followers, which while they eliminate scuffing and reduce friction losses in the valve gear also produce high contact loadings, while the bearing of the spinning roller requires a really good lubricant.

Unless you regularly do long runs, I would recommend an oil change every year or 8,000 miles. Given that, any synthetic oil will be fine, as no-one makes a bad oil! If, however, you regularly use your car for short runs, where the engine cannot thoroughly warm up, change the oil at something like 2,000 mile intervals. I once heard of an owner who commuted every day across town – a two-mile run of stop-start traffic – which is about the worst treatment an engine can have.

I would avoid ‘Longlife’ oils, unless you are one of the owners who never changes the oil unless the Service Indicator tells them to, when maybe two years will pass before this happens – not a good way to treat an engine.

Some enthusiasts doubt if an oil for a diesel engine can be also suitable for their high-revving petrol engine, but most modern oils are equally at home inside petrol or diesel engines, with or without turbochargers. An oil which is also suitable for a diesel has the advantage of a high detergency level, so will help keep your engine clean. For example, I used to use Volkswagen Quantum (made by Esso) a ‘straight’ mineral10-40 SJ turbo petrol or diesel oil in my 150 bhp Golf GTI and Heather’s 170 bhp VW Corrado, both their highly tuned 1.9 litre engines regularly running to 7,500 rpm (particularly during sprint events) with no problems whatever.

While on holiday in Poland with one of our Golf GTIs the engine developed a chronic misfire on one cylinder at low speeds, with a tappety rattle - obvious symptoms of a sticky hydraulic tappet. We drove home, taking care not to rev it hard or let it idle for too long, and the following day I changed the oil from Castrol Magnatec to the VW Quantum I had bought for the lawnmower. After an hour’s drive the engine behaved normally, and the problem never returned in over 100,000 miles. After that demonstration I used Quantum until buying the Z3, even on my BMW motorcycles, where it was surprising how much cleaner the insides of the rocker covers became!

Another easy way to select an oil is to look at the website; input your car details and see what options are given. Opie deliver by the next day to most parts of the UK. I have been using them for years, my choice being Fuchs Titan 5-40 petrol/diesel synthetic, as it enables me to use the same oil in the Z3, Golf TDI – and lawnmower!