When it comes to maintaining the V12, alot of people are thinking that the 750 needs specific 750 parts, when it's comes to the engine. That isn't the case.
Basically, and some people are not gonna like this, the V12 isn't really anymore than 2 M20 engine's welded together and by coincidence are sharing the same crank. To ensure that always 1 bank will run in case of a failure, every bank has his own injection and ignition system.
That means the V12 has 2 fuel pumps, 2 fuel filters, 2 separate rails with injectors, 2 cats, 2 lambda's (o2) sensors, 2 distributor caps, 2 rotor arms, 2 airflow meters (also known as MAF's), 2 crankshaft positioning sensors, 2 cilinder identification sensors, 2 intake temperature sensors, 2 coolant temparature sensors (and 1 in addition for the EML, making it 3 in total), 2 sets of spark plug wires, 2 air filters, 2 throttle bodies, 2 camshafts and last but not least: 2 DME Motronic computers. Even the oil pump is a tandem-type. The only part both banks share are the EML computer (basically a computer which synchronize both banks), timing chain, oil filter and the part of the exhaust system after the cats. And all of that for the price of one car.....sounds like a good deal isn't it?
It's this kind of redundancy which makes your car reliable, in that way that when 1 particular part fails (for instance, a fuel pump) you often can drive further with the other bank. The EML computer recognizes a difference between the banks and is shutting the troublesome bank down. Remember, we are talking about 1988 (even 1987 in Europe) when this boeing_on_wheels is introduced.....pretty impressive....
It's also this redundancy which makes it an expensive car to maintain. Buying 2 distributor caps, along with 2 air filters can make it a hefty maintenance interval due to the costs.
Fortunately, because of the similarities with the M20 engine a lot of 750 parts are interchangeable with parts from other bimmers. I tried to make a summery of all cross-references with parts you can use from other models. Most of it tested on my own 750. Hope this can be of any help. If you find out any differences, additions or errors, please report it to me (email adress on homepage).
This summary is divided into these sections:
Normally, I don't use any kind of filter from Fram. Air neither oil. I just don't like it and in my opinion it's an inferior brand. But my supplier didn't have anything else in stock, so I used them. I strongly advice you use a filter from a decent brand like Mahle, Knecht, Hengst, Mann or something like that. You can use 2 filters from the following models:
Not very easy to replace, but you can use also these filters:
At the right the original 750 cap, at the left a imitation from a 5 series. It fitted and it ran without any noticeable difference. It's a common part, used on various other bimmers:
Another common part, same models (not surprisingly) as the dist cap:
Also Alfa Romeo is using this kind of rotor. Not that you're interested, but I like to express my knowledge.
Throughout the production of the 750, 2 types of oil filters are used. At the right side the big filter, used from 1987-1991 and at the left the small filter, used from 1991-1994. The big filter is specially designed for the 750, no other filter can be used. The small filter comes from the 730/740 (v8). You can identify your type of filter with this: if the lid of the canister has a separate bolt then you have the big filter:
|old type, big canister,
lid has a separate bolt
|new type, small
bolt and lid are in 1 piece
Some serious remark must be made here: it is possible that the big oil canister is retrofitted with a kit to fit the small oil filter. A bmw service bulletin is about this procedure. On my car, a '88 750i, the retrofit kit is installed. I didn't know that, so I bought the big oil filter. There was no way I could get this installed. After much hassling and calling with people who should know but didn't know a thing, I found out that I needed the small filter. Well, always nice to have 2 filters when you want to make a photo to clear things up for other people.....
You can recognize the retrofit kit when looking inside the big oil canister. If you see a black plastic 'thing' in the center like this:
you must use the small filter. Cross references for the small filter:
As said, the big filter doesn't have cross references with other models.
Last remark: buy a decent brand. Again, my experiences with Mann/Mahle/Knecht/Hengst are very good. But you can buy also a filter at your local BMW dealer. They are not that expensive. If you want to know more about oil filters, brands and qualities, read this page.
Although this page is about cross references, I'll (I cannot help myself, I must tell this) explain the only right way to replace an oil filter on a BMW.
12 steps for an oil change? Yep, 12 steps for an oil change. This procedure ensures you have oil pressure when starting the engine. I am getting very nervous when there is no oil pressure in my main bearings and I am looking at an burning oil pressure light after an oil change, although its just for a couple of heart-aching seconds. I want instant oil pressure. Period.
The bad news is that the spark plug wire set (2 separate sets, one for each bank) is unique to the V12. And worst of all, this set is expensive. I mean really expensive. Enough to put you in a real depressing mood, considering seriously to sell the car and buy yourself a nice Acura (...)
But wait. Don't sell it yet. There is hope. The good news is that with some modification, you can use an E32 735i set. Of course you need 2 of them. I have written a comprehensive article about this here.
I have no affiliation with any firm whatsoever, all mentioned brands are used based on my own personal experiences.
If you would like to add any comments, remarks and/or corrections to this procedure, feel free to email Mike Oswald and we'll put it on our site. Share your experiencies with us so others may benefit from it.