Hello folks

I have a 1988 740 wagon non-turbo 8 valve aw-70 a.t. runs well for mileage in the upper 430,000 range. However sometime ago I had to replace the fuel assembly unit for typical corrosion reasons, but not before it leaked enough gas to errode my rear differential gasket. This of course caused gear oil leakage. I would have to put 2 qts in the rear axle every 5-6 days. It has already begun to whine, although not that severely. Could I possibly replace the rear diff gasket and refill the axle. I plan on eventually replacing the rear axle, but I figured as long as the axle gear oil was up to level/new gasket that I could get by with this for the winter. Most of my commute is hwy mileage. I know the whining may not go away, although it really is not too noticable. Also I usually put in 75w-90 mobil 1, however, could I just mix in some dino 80w-90, with some dino 85w-140, or would that be a bit over the top, and further complicate matters, especially with the winter fast approaching?

Please all of your help would be greatly appreciated!


Best Regards