As far as your questions go,
1. I run royal purple synchromax with no issues or grinding (160k miles on transmission)
2. Not necessary to replace the trans to engine bolts, they are two different sizes though. The two on the upper bell housing are smaller IIRC. If you're going to work on your own car, just go ahead and get a whole set of torx bits.
3. No need to drain the diff to replace the driveshaft. The CV on the rear of the driveshaft bolts onto a mating flange on the diff that then goes through the pinion shaft seal. Recommend knocking the studs out of the driveshaft CV before installation to make it a lot easier to get in without pinching the CV boot.
4. You are correct about the gasket, replacement is impossible without removing the flywheel. I replaced mine for peace of mind, but there were no signs of leakage. I would recommend a pressure test before installing your flywheel/clutch to make sure you don't have any issues.
I assume you are aware of the chatter you're going to get with a lightweight flywheel. If you're not supercharged, I'd recommend the OEM flywheel with the south bend stage 2 daily. You can find the LuK DMFs for ~$350 if you shop around. I wouldn't bother replacing the clutch fork and the guide tube only needs to be replaced if its damaged, mine wasn't at 160k so I didn't bother. You're going to have to pull the driveshaft to do all this anyways, so depending on your mileage you may as well pick up a rebuild one. Driveshaft Specialist Inc
has been used by many people on this board as well as myself and they are good quality for money.
I see Synchromax is widely accepted, so must not be necessary to use 'GL-4 spec'?
Ive read a lot of testimonies about the lightweight flywheel, I figure my car already sounds like a diesel (vanos). And I have no idea what setup I'm running right now since the car has 0 history (Owned for just over a year now, 7k hard driven miles ~152k presently and no other issues)
I figure the endurance kit might handle more abuse and last longer?
As for the driveshaft, is that for preventative maintenance? Is it common to replace it before signs of failure?
Ive read horror stories of the guibo failing under acceleration and airbags deploying.
Regarding the poly trans bushings, think hard about this as the NVH will be ridiculous. I swapped mine with UUC Black and I couldn't stand it. Had to switch back to stock.
You're missing the 6 or so bolt washer/gaskets for the rear main seal flange. They are basically washers with an integrated seal for each bolt.
Figure on replacing the transmission input seal.
I did replace the release bearing guide tube. Mine was pretty scored after 130K. This is not a lubricated part (do not grease it) so it kinda relies on the release bearing's plastic surface and wears inherently. Personally I'd replace it.
There is a particular grease from BMW to lightly grease the trans splines as well as the fork pivot points. I'm sure other greases would do but I didn't want to do it again so I used the actual BMW grease FWIW.
You'll want the pilot bearing puller, special torx bit for the flywheel, trans jack, and the flywheel lock tool. Sell them after the job, but IMO it's worth it to have the real tools.
Advice taken, definitely don't want to change the trans bushings twice.
Would've never known the washers act as a sealer, getting those!
As for the transmission input seal, should i get the output seal as well?
Guide tube stays in the shopping cart.
BMW Grease, check.
The guide tube is inexpensive and should always be changed. I've never seen one that didn't have wear on it. I would go with stock trans mounts too as anything else is going to increase NVH substantially for little gain. Then again, you're looking at a solid lightweight flywheel, so I assume you're prepared for the substantial rollover noise that will come with that.
Got it, guide tube is $58, not too bad.
As for the lightweight flywheel, the videos i found online with cars idling sound like mine already lol. The PO got the car from someone else and had it for literally months before he flipped it. History is unknown beside rod bearings being done around 90k lol. Anyway i drive it hard and it takes the abuse well.
This is why I'm figuring this clutch/flywheel combo, If i went to the LUK Dual Mass and Stage 2 Daily clutch that aligoodn suggests, would that be a step down in performance and longevity?