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I went to do my homework on the new RX8 and got a manual transmission oil change, differential oil change, and plain old engine oil change. I was clear with the service tech initially that the car needed GL-4 oil in the tranny, and GL-5 in the diff. I also said I wanted synthetic oil for the engine. After a couple hours the car was done. Tech tells me they put mineral (dino) oil in it because anything else will wreck the apex seals (o.0). I know the car can run fine on dino oil so I didn't make a fuss. However, looking at the invoice, I got a bit worried about what went in my tranny and diff:
So, looking at this they put the same oil in both the tranny and the diff, with some friction additive for the diff. Does that sound right to you? Since the tranny is supposed to take in GL-4, and the diff GL-5, I feel like something is wrong here.
They should have used the proper GL-4 in the trans, The GL-5 can cause damage to the synchronizers in the trans over time and can accelerate wear. Its great in the differential because it provides more extreme pressure protection over the GL-4. I would drain the GL-4 out of the trans and install the proper GL-4 gear oil. It will still be a 75W90 weight, it will just be API GL-4 rated.
The diff service seems to have been done correctly as well as the oil change. Mazda does not recommend the use of synthetic oil in the engine. Some people swear by it, I personally have never installed it in any of my 7's or 8's.
Just gave the dealership a call about it. They acknowledge that they put the same oil in for both the tranny and diff, but are adamant that according to Mazda Canada - and despite what the owner's manual says - the oil that went in is 100% correct and will not cause any issue. The master tech claims this info is straight from Mazda and unavailable to me otherwise. I think I'll ring up Mazda Canada just to see what they have to say. I suppose I'll have to dump the oil myself and change it for Redline MT-90 or something like that.
So yesterday I changed the tranny oil for Redline MT-90. Within about 30mins or driving I could feel a difference. 2nd gear engages much smoother, and it's just a better experience overall. Still can't say it shifts as well as, let's say, a 8th gen Civic SI transmission - which is the best I've ever tried, with maybe an S2000. Often I can feel the transmission shudder a bit when engaging 1st from a stop. Of course, clutch is in all the way. Anybody experiencing that too? Should I bleed the clutch? Engagement point feels nice and progressive.
There should be no trans shudder when engaging 1st gear. Should be smooth. I try however not to put the trans in first unless I'm stopped or at such a slow speed that its necessary.
