Used Castrol Syntec 5w50 in all my Honda trannys and never a problem...including my ITR which has 80,000km and ran Syntec since 10k.

Here at the shop, we install either Syntec, Redline MTL or Lightweight Shockproof for racers...again NO PROBLEMS....

But people will use what they feel comfortable with.

BTW, I have traced many shifting problems to leaking slave cylinders and masters.......when they start to fail....it seems like the syptoms most people talk about....