Oil type for my application?
 

Been reading all the oil threads, and not sure what oil I should go with. Bought the car used few months ago, has 65000 kms, not sure what oil previous owner was using but it looks like he had some mods then returned it to stock....so my guess is he would have been using synthetic?? I thought I could smell gas on dipstick after month of owning the car and oil did not look clean (guessing the dealer just slapped a sticker on the windsheld and good to go). So called mazda and they said they put regular 5W30, which ive been running for about 3000 kms (not miles) and there isnt a noticable gas smell like before. I want to use rotella t6 but now im not sure if I am risking leaking turbo seals by guessing and switching oils like this. What would you guys do? Go with the T6 5W40?? Is that ok to run on stock setup?? Plan on doing a few mods in couple weeks anyways. Any input would help alot

Its a 2008.5 btw

I don't think your going to hurt anything by running the t6 only thing that will happen is positive as far as I know. I know our cars stock are recommended to run on synthetic so not sure why mazda said 5w30 non synth. Heard good things about shell rotella but never ran it. I ran penzoil platinum thought I was doing my engine a favor and it blew up so I guess you never know.

Yes the top 2 on speedforums is PP and T6. I also read that swiching can cause turbo seals to leak. Is yours a Gen2? Gen1 owners manual recommends 5W30

Don't buy into all the oil hype. The guys that know, the used oil analysis guys (Blackstone, etc), all say that oil is oil, and either petroleum or synthetic-based oil will work well for just about any engine. Also automotive engine manufacturers know the principals of motor oils. They take these into account when they write that owners manual. So RTFM. My manual dose NOT say to use synthetic, just 5W30 that is certified for gasoline engines.

That being said I use synthetic in any high stress engine (i.e. turbo applications). I also use the OEM recommended viscosity 5W30. And I use a reputable brand and stay with that brand (although I did just switch brands because my favorite just swapped prices with my previous oil). I'll run this brand for at least the next 20k regardless of price. My last UOA showed that after 2 track weekends 15-20 sessions my 5W30 had sheered to 5W20 and it was good that I changed it but there were no differences than that over the previous UOA that had 4k everyday miles. Basically proving this nitpicking over oil is pointless.

TLDR;
Pick a quality 5W30 and stick with it. If synthetic makes you sleep well at night go synthetic.

^^^ This. Any SN rated 5W-30 or 5W-40 will work fine. Assuming both oils are SN rated, anyone who says that oil ABC is made from unicorn tears and that oil XYZ is crap is talking out of their butt.

I just have a unicorn piss in my oil fill.

But in reality. Oil is oil. I have been using amsoil 5w-30 changed every 2500-3000 miles (cause I am stupid) for the last 97k miles on my stock motor and stock turbo. Not sure if I will make the switch to T6 or 5W-40. I would definitely do an oil analysis every now and again and just try to stick to a good interval and check it often.

If you stay on top of this car as far as maintenance and checks you should have nothing to worry about.

BTW belated congrats on buying your speed!