How quickly after a fresh rebuild should I change the oil?

[lelandEOD]

I just finished a 18 month rebuild of the 3FE I’m running in my –40. After troubleshooting an open circuit in the airflow meter, it’s now running although I still have a mysterious lean-miss to solve. While I diagnose the mixture problem, I’m wondering at what point I should dump this oil and filter? I have only driven it down the street once and it’s been running for about 20 minutes total.

Should I give it more time to break-in more before dumping the oil or should I get rid of it now since it’s contaminated with assembly lube and such?

Opinions?

 

[lelandEOD]

Obligatory photos:

 

[shawnfj40]

I don’t normally change it until around 500 miles or 40 hours run time. That’s just my preference though and not necessarily the right thing to do. There’s lots of different break in procedures and differ between lots of factors. It’s especially different if you’re using full synthetic or conventional oil.

 

[4x4veteran]

I don’t normally change it until around 500 miles or 40 hours run time. That’s just my preference though and not necessarily the right thing to do. There’s lots of different break in procedures and differ between lots of factors. It’s especially different if you’re using full synthetic or conventional oil.

That was the rule of thumb I learned by and after a half dozen engine rebuild have had no problem from going by it.
You do not want to run it too hard during break-in but do want to very the rpm's during break in versus one constant speed.
In the past I always used 20 weight non-detergent Valvoline but a lot of mechanics are using Rotila now.

 

[coonassjohn]

40 hrs. or 500 miles could be too long in some cases. Depends on your conditions and amount of driving you do. Whenever you do change cut the filter open and inspect for any foreign material that may be present. Filter cutters are available at most aircraft tool companies and are very good tools to have. By the way, Nice Conversion! Looks like you had to use a shoe horn, but really nice.

 

[lelandEOD]

Thanks everyone. I think I’m still going to change it before 40 hours but that is a good baseline and at least I know I’m not doing damage by not changing it immediately after fire up.

 

[Pommy]

Hey mate

I work as an aircraft engineer rebuilding piston engines and we generally run our engines in for 3-8 hours before dumping and filtering the oil and, as John mentioned above, cut open the oil filter and inspect the paper inside for metal contamination.

Vary your rpm steadily and build up to reasonable revs for a few minutes before slowing them back down always keeping an eye on temperature and oil pressure. If you just keep it ticking over at idle for hours of small 20 minute sessions you probably won’t bed the piston rings in effectively and will have lower compression after your break in period.

Happy to help if you have questions

Ash