Article reproduced with kind permission of Mike Fishwick
Many owners are terrified of losing that string of BMW Dealer stamps in their service book, believing that such expenditure may gain a better trade-in value or an easier private sale. Although this has a logic in terms of fairly new cars, an investment of maybe several thousand pounds will never be redeemed on a long-term car deemed by the trade to be virtually ‘worthless.’ Such a car is my old (1998) and high-mileage (87,000 miles) 2.8 litre Z3. If such a car were ever sold its condition would be of far greater importance than a string of expensive oil changes. I am therefore a firm believer in doing as much work on my car as possible, including twice-yearly oil changes at a frequency of 8 to 10,000 miles. My current choice is Fuchs Titan SL PD 5-40 full synthetic, from Opie Oils of Redruth, the ‘PD’ suffix meaning that it can also used on our VW Golf TDI.
Simple tasks such as changing the engine oil and filter can be easily performed by the owner, and quite apart from the obvious cost saving, can be performed to a higher standard than is, regrettably, now the case at many BMW dealers. For example, it is quite common to find that the oil is not drained, but removed by suction via the dipstick orifice, á la Quick-Fit etc, while the critical small ‘O’ rings within the filter housing are seldom – if ever – replaced.
It is never certain that a ‘professional’ oil change has taken place while the oil is hot, when any sludge formation has been dissolved into it. Draining cold oil is never guaranteed to leave the inside of the engine in a clean condition.
In some cases it has afterwards been found that the oil level is too high – sometimes by up to a litre! This problem is presumably due to a combination of not removing all the old oil, followed by filling with the correct volume and not checking the level afterwards. In a regime where only 15 minutes is allocated for an oil and filter change, this type of problem can be expected. On certain engines it can be critical.
The usual manuals such as Haynes and Bentley give general descriptions of changing the oil and filter, but can be improved. These are the main points I have found over the years:
Replacement of the spin-on filters found on older engines is self-explanatory, but it is worth remembering that this task is often eased by use of a cup wrench, designed to engage with the multi-faceted base of the filter. In many cases the filter can be filled with oil before fitting, so providing a good oil supply from start-up.
The later engines, however, require a little more thought. There are three types of oil filter cover, the aluminium type, which is secured by a long bolt with a 13 mm head. The larger plastic type, used on most later six cylinder engines, requires a 36 mm socket to unscrew it. The smaller plastic cover on engines such as the 1.9 litre M44, requires a special cup wrench which is available from German & Swedish outlets at about £10.
Removing filter cover on 6-cylinder engines with 36mm socket
As the plastic filter cover is unscrewed it lifts a rod attached to the cover, which opens a gallery draining the oil from around the filter into the sump. Removal of the long bolt from the metal cover performs the same task. It is therefore necessary to remove the filter before draining the sump, otherwise the new oil will be contaminated by the old filter oil. For this reason always replace the filter first.
Remember to lightly oil the large ‘O’ ring before fitting to its groove above the top of the cover threads, and take care not to twist it. A dry ‘O’ ring can prevent the cover from unscrewing, and it may have to be cut off. The filter element is a fairly tight fit around the spigots in the cover and at the base of the filter compartment, so expect odd squeaking noises as the cover is screwed down.
FILTER DRAIN SEALS:
No mention is ever made in the popular manuals of the small ‘O’ rings which seal the filter compartment drain gallery – although they are clearly shown on the BMW TIS (manual), and ETK (parts list). The plastic filter covers are fitted with two these ‘O’ rings, while the metal cover uses one, on the base of its securing bolt. (Their part number is 18.104.22.1684.001)
Oil filter cover and internals – note small ‘O’ rings
These rings play a vital role – if they leak, pressurised oil from the filter is permitted to escape into the sump, so by-passing the bearings! A failure of these rings could therefore be disastrous, and repeated use of them is the surest way to wreck your engine. I remember reading of an M Roadster owner whose crankshaft bearings seized to the shaft and spun in their housings, so wrecking the crankcase . . . just after having had the oil and filter changed! If your car has had a filter change, check the invoice to see if these vital components have been replaced, and object strongly if they have not.
Neither the BMW or German & Swedish filter kits include these rings, although the BMW manual (on the TIS CD) states that they must be replaced with each filter. Even BMW dealerships do not however replace them – I checked with my local dealership, who had fitted 12,000 filters in the past year, and ordered 8 (yes, eight!) small ‘O’ rings . . . and those 8 had been ordered for me!
As the drain plug is on the right (i.e. offside) of the sump, jacking the car up at the right side will leave a bit of oil in the left side of the sump. For this reason I always jack my car on the left, which raises it sufficiently to get at the drain plug, and also tilts the car to the right, so completely draining the sump. I use the ring end of a combination spanner, positioned with negative offset so it does not slip off the hexagon. I drain the oil into a metal tray fitted with a tap, which enables the old oil to be poured back into a container without any mess, but suitable plastic trays are available. Most local authorities will accept old oil for disposal without charge.
Un fastening sump drain plug – note spanner in inverted position to avoid slipping off
As a safety measure, place the drain plug on top of the new oil container – you would not be the first to refill the engine without replacing the drain plug!
BMW fit the drain plug with a hollow aluminium crush washer, but having seen the result of these fracturing, and permitting the drain plug to come loose, I prefer to use a solid copper washer. After fully draining the sump, replace the drain plug, and tighten fully by hand, using about 15 cm of leverage on the spanner. Do not use a torque wrench set to the maker’s figure, as this is for use when building a new engine, with threads which are dry, and not coated in oil.
Initially fill the sump, using a measured quantity of oil, to a point halfway between the ‘Min’ and ‘Max’ marks on the dipstick. Remember that the filter will be empty, as it cannot be primed by being filled before the cover is fitted, for the drain passage to the sump will be open until the cover is fully tightened.
It is therefore good practice to prime the oil system before starting, by operating the starter motor in very short bursts until the low oil pressure light is extinguished while cranking. Remove the fuel pump fuses to prevent the engine from starting, and on older engines, with coil and distributor-type ignition systems, isolate the coil and remove the spark plugs. When pressure has been fully established start the engine, and allow it to idle for a couple of minutes, then stop. Do not rev the engine, particularly if it is turbocharged, as the bearings will initially be fed with an aerated oil supply.
The ideal modification for filters with the metal cover is to buy a UUC filter cover (or ‘Oil Center,’ as they refer to it). This solid aluminium cover has threaded outlets in the sides for oil pressure and temperature sensors, which can be fitted with suitable plugs, and used to fill the filter housing before start-up. Unfortunately UUC do not manufacture covers to replace the plastic types.
After a minute or so check the oil level, and adjust until the level is half-way between the ‘Max’ and ‘Min’ marks – this will generally be the rated oil capacity, which in the case of my 2.8 is 6.5 Litres, whereas filling to the ‘Max’ mark requires 7 litres. This will prevent any risk of the oil being ‘frothed’ by windage from, or contact with the crankshaft, and also reduces any oil consumption. Regard the ‘Max’ mark as a limit, rather than a target.
If your engine tends to burn oil, do not continually top up to the ‘Max’ mark, as the initial amount is always burnt faster than the remainder of the oil. There is no bonus for filling to the ‘Max’ mark, the specified volume being more important.
Accurately fill to a new mark, filed on the dipstick between the ‘Min’ and ‘Max’ marks. Allow it to drop to the ‘Min’ mark before refilling, accurately logging the mileage and volume used, a practice which will give a clear indication of the average consumption rate. You will, however, need to monitor the oil level more closely than usual, as the difference between the new ‘Max’ and the old ‘Min’ marks will be about half that of the original.
Some modern BMW engines are developing a reputation for high oil consumption when compared to their older cousins, a litre every 5,000 miles not being uncommon on the M54 three litre engine, for example.
While such rates of oil consumption are not high by historical standards, it remains galling for owners of the Bavarians’ latest to find that the older cars do not consume oil at all. At least a known thirst for oil should force owners to lift the bonnet, and find where the dipstick lives – although I have heard of one owner who paid a dealer to perform such mind-bending tasks!
Too many owners rely on the Low Oil Level warning lamp, and many new engines do not even have a dipstick, yet they do not carry any spare oil. If you are not going to check and top up your oil regularly, then carry a litre in the boot. Remember – the low oil level warning only operates when the oil reaches the ‘Min’ end of the dipstick.
A probable reason for this relatively high consumption is the use of ‘Long Life’ synthetic oil. These lubricants are wonderful things, reducing friction and wear, while warding off the effects of water and acids formed by the combustion process. Even with modern machining techniques however, there is still a small amount of running-in required. The use of a synthetic oil will act to prevent the associated bedding-in, so extending the running-in mileage considerably.
It is worth remembering that piston rings prefer a running-in regime of high speed and light load, rather then the ‘kid glove’ approach to a new engine adopted by many owners. When combined with synthetic oil, the lack of bedding-in may mean that an engine can cover up to 40,000 miles before running-in is complete, and oil consumption falls.
The use of an ordinary mineral oil for the first 10,000 miles or so, with at least one oil change, was recommended many years ago in a BMW Service Instruction. The current astronomic labour charges, however, mean that today’s owners have come to regard extended service intervals as a sign of progress. Most modern engines are therefore subjected to extended oil change intervals of up to 20,000 miles.
This can, however, act against the interests of the engine, particularly in the long term. For example, experience has shown that Volkswagen’s 1.8 litre turbocharged petrol engine, used in the Golf and Audi TT, slowly develops sludge deposits when its diet of Castrol SLX is replaced at extended service intervals – and possibly on a cold engine.
These partially obstruct the mesh filter of the oil pump pick-up, reducing the flow rate, but not sufficiently to reduce the oil pressure. As no low oil pressure alarm is given, the vehicle continues to be driven, until problems arise at about 100,000 miles. The camshaft timing unit (VW’s equivalent to VANOS) is the first to fail, closely followed by the camshaft bearings and hydraulic tappets. With this combination of age, mileage, and mechanical mayhem, several much-loved cars have had to be written off – what price extended service intervals?
BMW Oil and Filter Changes by Mike Fishwick
Many owners are terrified of losing that string of BMW Dealer stamps in their service book, believing that such expenditure may gain a better trade-in value or an easier private sale. Although this has a logic in terms of fairly new cars, an investment of maybe several thousand pounds will never be redeemed on a long-term car deemed by the trade to be virtually ‘worthless.’