Better to change oil before or after track day?
 

I have a 2015 BRZ and just signed up for a high-speed touring day at the local track. My car is coming up on 6 months old and has just under 3k miles. I plan to change the brake fluid before the track day. My question is about the oil. I changed the oil myself at about 1k back in November. Would it be best to change again before the track day or wait until afterwards? FYI, I have Mobil1 0w-20 mixed with about 1 quart of Mobil1 0w-40 right now. Thanks for your input.

why mixed?

and if you changed your oil 2k ago, with no serious tracking between nov and now, should wait until after

seems excessive. but just my 2 cents

I was planning on a track day in late November about a week after I changed the oil. I thought adding a little 0w-40 would be beneficial for a track day. Unfortunately, we got our first snow that weekend and it got cancelled.

Just change it according to your regular interval. You do not need to change it right after a track day and there are many uoa's where people have multiple track sessions on the same oil. Plus the added viscosity, detergents, and TBN in M1 0W40 will help. I would probably run your fill to 6k miles.

As others have already said, you're being slightly excessive. Just follow regular oil change intervals and check oil before each track day. If you're low, top off. That is about all you really need to worry about as frequent high revs will eat up oil significantly faster than normal or spirited driving.

I would personally change it after track day. But that is just me.

If you still have the factory fill & is at 3k now. Changing right after a track day doesn't sound like a bad idea. :w00t:

A bit excessive, but if you're going to do it do it after the track day. The idea is to get rid of the oil that's been exposed to really high temperatures and oil that may have sheared grades. Again not 100% necessary with good modern synthetics that often, but there's no real harm other than in the wallet so people do it for assurances.

I have 50 track days on a '13 BRZ. totally stock car. also 30 yrs. SCCA and PCA race experience. I have done many oil analyses on my cars.
I run exclusively 0W-40 Mobil 1 because it has a synthetic base stock. Most synthetic oils today do NOT come from a synthetic base stock. (check with your oil mfg. if you dont believe me) Change your oil and filter after every other track weekend and you will be fine. High oil temps on the track break down the additives and base stock so do not stretch oil change interval. Most importantly, check oil level after every on track session. FRS and BRZ motors use oil at sustained high RPM.

Like I said in the other thread, your information is wrong. Do some research on Exxon-Mobil's Visom base stock. Synthetic is just a marketing term anyway.

My experience and UOA so far with ENEOS Sustina contradict your experience.

-alex

So it sounds like the OP is doing the right thing by mixing in 0W-40? I also use Mobile 1 for track days but I'm 100% 0W-20.

Adding in 0W40 will slightly bump up the viscosity, the High Temp High Shear, the detergent levels, and the anti-wear additives.

Whether or not it is helpful or detrimental over the long term is another debate. Many people have been mixing oil for years while others say that it shouldn't be done on a regular basis since the two oils were not engineered to work together and you are affecting the cold cranking viscosity by mixing. Of course, cold cranking viscosity is not so important during track season though.

"Shannow" on bob is the oil guy is very much against mixing oils:
http://www.bobistheoilguy.com/forums...for_Oil_Change?
Unlike many people there, he usually provides data for his statements instead of just expressing an opinion. His experience is in the design of bearings. This might really be splitting hairs if you're doing short-ish runs on the oil, but you can read that link and make your own decision. :)

And if you think by using something like regular Mobil1 5W-30 or 0W30 you'd be bumping up your viscosity, these oils actually shear to a 20 grade under hard use so you do not necessarily end up with a thicker viscosity (although you do get more ZDDP). If you're concerned about wear and protection, I would at least run Mobil1 5W20 or Mobil1 0W20 EP over M1 0W20 AFE due to the higher ZDDP in those as well. Or perhaps Mobil1 xW30 for the additional ZDDP and maybe a slight bump in operational viscosity.

M1 ZDDP info here:
https://mobiloil.com/~/media/amer/us...ecs-guide.ashx

This site provides a viscosity calculator for mixing oils so if you really want to get to a precise viscosity:
http://www.widman.biz/English/Calculators/Mixtures.html

Some oil companies say that it's fine to mix their oils if you're mixing oils within the same family (e.g. Mobil1 AFE, Mobil1 EP, Red Line street oil, etc.). I don't recall if XOM said that, but it's probably best to contact the manufacturer for their opinion.