OK so my new motor is FINALLY in the car, it is being run in on Penrite Running in oil 15w - 40. Now I am due to drop the oil tomorrow to change it as it has been almost 500km's. My questions are, do I go the same weight oil in a semi synth for the next few thousand km or straight to full Synth?

Can I run a lighter oil or should I really stick with the weight that it was run in on?

Personally I prefer Penrite oil and look to run this on HPR 10, its a semi anyways, but I am aware there has been some debate recently about the quality of Penrite. If the opinionated FNQ'r would like to put his suggestions/advise here it would actually be appreciated, and others of course.

What is your routine for running in motors as far as type of oil used goes.. People who have actually done it, not those with 5c comments please.

What engine is it exactly and is it a full reco with new rings and pistons???

yeah sorry, its a full reco, has 30cc dish top forged pistons, Manley rods, file finish rings, honed block, no need to bore, linished crank, ported and polished head. Has been run in on Penrite run in oil as previously mentioned, tomorrow will see 500km on the motor so time to drop the oil.

I kept using running-in oil until 1000km, but then some people would say that's an overkill. After, I used Nulon 15w50 Street and Track performance (synthetic) oil. Haven't had any oil loss since. Perhaps go with the Penrite oil until your next oil change and then swap to a synthetic oil.

Have the rings bedded in OK (ie. is the oil level still the same as when you filled in initially)?

yeah oil level is stable. 500km is all it will need.

i went through all this recently.. and went penrite running in oil for 500 (15w40) then nulon 10w30 for 500km and more nulon 10w30 for another 500km..and then onto penrite 5w40 semi synthetic since..7000km's so far and not using a drop of oil..

I'd drop it down to a 5w-40 full synth and see how it goes, Ive changed to shell helix ultra 5w-40 after using fords 10w-30 without any problems. I find the shell oil to be excellent, after 5000km the oil is still golden and just like it came out of the bottle.

Obviously this isn't a toy engine. or you wouldn't have used all the good gear in it.
If it were my engine i would be using one of two oils in it,
Mobile1 0W40 synthetic OR Motul 300V chrono (10W40), my preference is for the Motul (is what i used to use in my built EFxr6 engine when i had the car.)
both cost alot, but both are extremely good.

As far as runnung in goes. i went 500km befor going straight to the 300V, and never had an issue.
If you want to 'play it safe' go with a semi synth from what ever brand you end up going too.

I run the new engine in my mighty boy in on Bursons running in oil for not quite 1000kms, it's a SAE30 iirc, and then i just run what the book says, 10w40 mineral oil. Engine was rebored, crank ground, new pistons, bearings & rings, full head reco with port work & new valves. It's running great, has now got 2000kms on it. Time for another oil & filter change, i tend to do them every 1000kms until the first 5000kms on my fresh engines. Then it's by the book.

Most mechanics i speak to suggest to run the run in oils for anywhere between 500 to 1000kms, then change it, but not to run past 1000kms on it.

Cheers

ToranaGuy