Just several questions

Hello

I have Oldsmobile Alero 2001 GLS 2.4L with 128 000 km.
Unfortunatelly , I not familiar with GM cars . So ,I have several simple questions. Any answer will be highly appreciated.

1. The oil recommended by dealer in my country is 10W40.
Las time , the mechanic had put 15W40 instead. According to service manual , this is possible to use 15W40 for 2.4L engine. Do I need ask mechanic to clean motor with special cleaning fluid before next oil change to 10W40?

2. The fuel recommended by dealer in my country is 95 lead free. I heard ,that Subaru one owner uses 98 octan to clean injectors etc. Is it harmful for engine ? Is it help , or injector cleaner fluid+ 95 lead free is better thing?

3. The 2.4L Alero engine is very noisy at RPM higher than 1000 . Does anybody know how to isolate cabin from engine and tires noise?

Thanks
Michael

1.No, i would use 10w-30 oil, it works better.
2.Nope, you can run safly up to 100oct. in any car.
3.Sounds like a lifter noice. Change oil woth 10w-30 and noice should get better. change oil every 5 thousand miles.
Do you speak french? I speak it as well.

I would stick with 5W-30 personally.

- Jeremy

I used 5w-30 and chewed it up in 2,500mi. thats why i said 10w30. I guess 10w-30 works better for me.

What do you mean 'chewed it up'? Did the engine burn it off?

- Jeremy

It was pure black water at 2500mi.

I use 5w30 Mobil1 synthetic, it works great for me.

Thanks for the info, it really helped me.

Regards
Michael