I don't think the oil type is critical as long as it's the right spec and a reputable brand. CC don't appear to either, in the past 7/8 years they've had 3 different 'preferred' suppliers.
Neither do I think a little cross mixing would be an issue, I had this discussion with Opie and they confirmed that as long as spec is maintained it wouldn't make any difference.
The fitting of a mag plug is a no brainer. It's a good indicator.
In the midst of my diff issues, I was quoted the Titan service requirements by CC. I take that as being CC's advice too and so they and their agents should require it during routine maintenance, IMO.
That's not to say they wouldn't charge for it but there seems little guidance when buying a car, perhaps because a £1-2k bill every 2 years or so might put some people off?
ScottR400D - I agree with your statement about oil type. Regardless of manufacturer/supplier as long as the oil is like for like - viscosity, synthetic, semi synthetic or mineral then there is not a problem.
If a decision was made to replace the oil with one of a different viscosity index, type (semi synth/mineral) then there should be some effort to remove as much residual as possible to avoid intermixing.
In aviation having seen what intemixing of oils can do to gearboxes & the like it is best avoided !
I'd agree with all that but wouldn't worry too much about the VI. I've seen all sorts of grades from 75/80 to be 75/150 recommended. I've used both ends of that spectrum and seen no difference in performance so going from one end to the other, after removing as much of the old as possible is going to leave a fill that pretty near what it's meant to be.
Of course, removing as much as possible is a given but I've found the Pela extractor quite efficient at emptying the BMW diff, leaving very little behind.
I am dumping my diff oil next month. Replacing with same Castrol B373 SAE 90. Its very viscous, stinks to high heaven & 'old fashioned' mineral oil but it works for me !
So following on from last year's results (mileage 2,400 and 1 track day: 42 lb.ft preload), I've just repeated the checks:
Mileage 4,500 and a further 3 track days: 42 lb.ft preload again
So far then, road and track driving in my car doesn't seem to be causing an issue. it'll be serviced in March (along with it's first MOT) after winter lay-up, so I think I'll get the diff oil changed then too as a precaution.
Gulf Racing 310R
Deleted original post. I've realised that we'll all have different experiences and believe what we want to. That's fair enough, have fun out there.
It doesn't matter what positive information is posted on this thread/forum about the synter plated Titan diffs, it will be shoot down by the mistakes from the past and the price owners have paid for the lack of information at the time.
My detailed build blog
It's your guide I've been using to check the preload Chris, so thank you for writing it
Changed Diff oil today as I thought that two year intervals were about right. So one year & eleven months & 3,518 miles later just a small amount of finings on the mag plug & the oil was quite dark. Grey but not black.
Fresh Castrol B373 back in for another two years.
I drove the car for twenty miles to warm the oil up so I thought that I would change the gear box oil as well as it has been in since build nearly ten years ago.
The drain plug well was full of finings & there were a few very, very minute feathery metal shards on the magnet nose. The colour indicated they were more than likely steel. The oil which is 80w90 mineral was NATO dark green in colour. Usually a light yellow with a green tint when new. So same oil back in for another ten years.
Just done over 2000 miles spirited driving in last 2 weeks round Scotland. Preload down to 43.5ft lbs from 44ft lbs (manual torque wrench). Electronic torque wrench shows around 1ft.lb drop. Car now up to 10700 miles in 18 months from new. At the moment radiator is bigger issue than the diff.