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Hi guys,

I am in he process of rebuilding my BP4W, it is back in the car and it should be running again in the next week or so.
I am going to use Castrol GTX 10W30 for the break in period then switch back to Castrol Edge synthetic after. Prior to the rebuild, I was using the Castrol Edge 10W60 and made sure I thoroughly warmed the engine up prior to driving.
My question is, what viscosity oil is best suited to a freshly rebuilt engine, warm Perth weather and the engine does get a fairly hard time with a turbo hanging off the side. The car is not a daily driver so I don't need an oil where I can start and instantly go.

Thanks,
Dale

You could use a purpose run in oil for the first 500km then drop it (and the filter) and replace with your chosen oil.

Royal Purple make a mineral running in oil.

Otherwise any fairly plain dyno oil should do. Avoid synthetics for run-in, they're too slippery and can lead to glazing. Castrol RX diesel oil is popular.

Maybe I confused people.
For initial startup and break in I will be using Castrol GTX 10W30 dino oil.

After the break in period, I will swap back over to Synthetic oil. I am interested in what viscosity oil people recommend AFTER the break in period.

I'm running Castrol Edge 10W-60 in my track car. I do a combination of sprints, track events etc so it's sometimes hard to get the engine at full operating temp.

So far so good.

HKS Super Racing 10w55
Max. Oil Temp. 150℃
100％ SYNTHETIC
SM-CF equivalent

It is road registered but does very few road KM's.

I just use 10w40.

Brand is whatever's on special when I buy it, and isn't "black and gold"

The engine has started and is being run in with dino Castrol GTX 10W-30.
So far so good with no strange noises and everything sounding sweet.

After about a 500km run in, I will switch over to fully Synthetic oil, I have it down to either Castrol Edge 0W-40 or 10W-60.
Does anyone have any experience with a rebuilt engine (forged rods/pistons, rebored and all new bearings) with a turbo in a warm climate? In the past I have used the 10W-60 and it seemed to work great, but now the engine has been freshened, maybe the 0W-40 might be better? or just stick with 10W-60?

Mine is not turbo but was honed and re-ringed and I wring the neck off it on every gear change. 700km break-in with some high-pressure pulls up hills to seat the rings. Since then I've used a mix of good 10W40s and 10W50s and it's lasted 3,000 competition laps, including stinking hot days, and maintained full compression. I don't think they're that fussy about viscosity. Just buy good stuff.