AutoCross: fresh oil, or change after?

[JamusMcFamus]

I have a ‘17 Miata with 50k miles. The oil currently in it has 4700 miles on it. I forgot to write down which brand I used, but it’s either Mobil 5w30 ESP, Castrol 5w30 LL, or Valvoline 5w30 XLIII (I believe). Regardless, they’re all the VW 504 type.

I have an autocross this weekend. Should I change it beforehand, or just run the course and change it after?

 

[Rod Knock]

Change it, just to be on the safe side.

 

[dogememe]

Change it, just to be on the safe side.

I disagree. Those are all quality oils. I’d change it after.

 

[ctechbob]

AX'ed a 91 Miata for many years. Just changed it on the normal 3k mile schedule for the car. 4-5 60 second runs isn't going to make much difference in the grand scheme of things. You're using a good oil, don't worry about it.

 

[Rod Knock]

I have a good feeling about this...

 

[JamusMcFamus]

I have a good feeling about this...

So if you were me, you would change it now, run the autocross, and then change it at what interval afterward? I’m leaning towards not changing it, but I’m interested in your opinion.

 

[JRed]

I'd change for something like a track day but wouldn't bother for an AutoX, especially considering you're running a good 5w30.

AutoX is probably easier on the engine than getting after it on some twisty mountain roads.

 

[atikovi]

What's so stressful to the engine during an autocross that you need to change the oil before or after? You're probably not going over 20 mph and not driving more than a mile or two at a time.

 

[ctechbob]

What's so stressful to the engine during an autocross that you need to change the oil before or after? You're probably not going over 20 mph and not driving more than a mile or two at a time.

Depending on the course/driver/car 45-65ish, but yes, its not as hard on cars as you'd think. Even bouncing off the rev limiter isn't going to warrant an oil change before or after unless the car is just due for one.

 

[IndyIan]

What's so stressful to the engine during an autocross that you need to change the oil before or after? You're probably not going over 20 mph and not driving more than a mile or two at a time.

Eh, depending on the course and your gearing, its not too unusual to run the car hard against the limiter in 2nd gear, and then slow down to below 3000 rpm and floor it back up to near the limiter again. That said, its not hard sustained running like on track day for a couple hours, so I never shortened my OCI's when doing autocross.

 

[Rod Knock]

So if you were me, you would change it now, run the autocross, and then change it at what interval afterward?

Oil is cheap, engines are not.

There is no objective data available about the condition of your engine. And there is no oil analysis available to asses the condition of the lubricant you're currently running in it. I find it rather unusual that you cannot recall what motor oil you used for your last oil change. I'm not faulting your for that, because not everyone has good long-term memory. However, you should keep accurate maintenance records. If nothing else, CARFAX offers a maintenance logging tool for free, and you can specify in the notes the lubricant you used for your oil change. Also, the mileage since your last oil change may not be accurate. How would I know? Conclusively, I made the safe recommendation and advised you to change your oil before attending. And no, you don't need to change it again after the auto cross event.

I’m leaning towards not changing it.

Then why start the thread and ask us?

But I’m interested in your opinion.

I think you're looking for information that supports your confirmation bias.

The reason why I jokingly said that "I have a good feeling about this" is because these types of threads have a tendency to run for ten pages or more. This happens because no clear conclusion is reached as all recommendations are essentially subjective opinions, including mine, as there is no objective information available to interpret.

 

[JamusMcFamus]

 

[DuckRyder]

I would change it whenever it's due on a time / miles basis. Presumably that is sometime after.

 

[JamusMcFamus]

I would change it whenever it's due on a time / miles basis. Presumably that is sometime after.

It was due to change at 5,000 miles anyways, so I’ll run the autox and change it next week.

 

[wpod]

Run the oil. It will hold up to all the abuse you will give that engine well beyond your oil change interval.

 

[SugarMouth]

Depends.

Is that 4700 miles of AutoX, track days and back roads or is it 4700 miles of daily driving under moderate city/hwy?

That makes the decision.

 

[ProbeGT]

I never thought of doing extra oil changes when I did AutoX in my Ford Probe GT with the Mazda 2.5L V6 and never had problems. That said, I went to an AutoX event in Austin last summer (to watch). A Mazda Miata went out with a bang. Threw a rod.

AutoX is hard on oil. High load and low speeds = lots of heat. February temps will help with that.