Jordan said:
With lower viscosity oil, the engine might rev more smoothly. Did the dealers use 5w30?
I think that might be the issue. They might have added too much oil because when I drained it, there was over a gallon.
@Brady
Maybe they did, some mechanics just pour a full 5L bottle when the car only needs 4.5 liters. They might not have checked carefully.
Jordan said:
@Brady
Maybe they did, some mechanics just pour a full 5L bottle when the car only needs 4.5 liters. They might not have checked carefully.
Oops, that careless mechanic is me. But honestly, my garage is full of 0.5L left in 5L jugs. And having 500ml extra oil won’t cause problems.
@Laken
I know it’s not a problem, but I pay mechanics for their work and expect them to do it right. The car needs 4.5 liters. Also, why not keep the extra 500ml and for every 9 oil changes you get 4.5L oil for free.
Usually, the engine should be quieter after changing to fresh oil. At least with mine, it never was noisy. I always used Pennzoil Platinum with the K&N oil filter, which I think is the best oil, at least for regular cars. Fresh oil has fewer impurities, which means less engine friction and less noise.
If your engine is louder, it might mean more friction, which isn’t necessarily bad since Quaker oil is probably fine. Some synthetic oils aren’t good and can’t handle the heat Mazda engines produce. If you smell something burning when you accelerate hard, that could indicate a problem.
@Xavi
There’s no smell, just a louder and stronger sound when I accelerate above 2000 rpm.