I have an R15v3 with 4.5km mileage, just recently I had no choice but to use semi synthetic oil because the shop I bought the oil from gave the wrong product, now I feel that my engine "roars" too early on each gears compared from before when I was still using the fully synthetic one.

My questions are:

  1. Is it a bad thing that my engine roars too early? (Or is it normal given my current mileage?)
  2. Should I change my engine oil right away? (I live in Philippines where it gets 32-38 hot, also there's significant traffic during daily commute)
  • Welcome to Motor Vehicle Maintenance & Repair! Commented Mar 10, 2021 at 0:47
  • Hey man, good to be here :)
    – Kent Abrio
    Commented Mar 10, 2021 at 0:51
  • 1
    Is that 4.5km or 4.5kkm? Either way, that not many miles. Is this the first oil change? Even so, the engine isn't even broke in yet (I wouldn't think). My thinking is, the "roars too early" part of this is more or less your imagination. Your R15v3 can only go a top speed of 84.5mph. It really doesn't have much power to start with. The only other thing I'd wonder about is whether the clutch is a wet clutch with an engine oil bath or a dry clutch (or even with its own reservoir). If a wet clutch fed by engine oil, its VERY important to be using what Yamaha calls for. Commented Mar 10, 2021 at 1:08
  • 4,500 Kilometers, this is the 3rd oil change
    – Kent Abrio
    Commented Mar 10, 2021 at 1:18
  • Yeah, might just be my imagination because I was to worried about the performance of the semi synthetic engine oil.
    – Kent Abrio
    Commented Mar 10, 2021 at 1:20

1 Answer 1


Using the wrong oil on a motorbike with a wet clutch can indeed cause a speed reduction... But not due to a change in the gearbox. The reduction in speed would be due to clutch slipping rather than anything else.

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