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hey guys just wondering what oil weight you would recommend for a fully built rb25 its oil change time and i was gonna go with redline 15-40w i have been using castrol edge titanium 15w60 but someone suggested this isnt a good weight for goldcoast during summer? i know this has probably been covered in the previous 152 pages but i dont have time to trawl and ive done a few searches but not really answered my question. so i thought i would get some opinions

anyways cheers for any replies

Ask the engine builder.

They put it together and know the tolerances.

iv always used the Castrol edge titanium 10w40 in W.A. summers and seemed to do the trick just fine.

Not sure about your built engine tolerances tho so the recommendation to check with the builder is a good one.

Nonetheless, as the motor was recommended stock to run 7.5W30, I think 10w40 is a good number for these older motors and warmer conditions. Also a fully syn is far beyond the requirements the guidelines note.

I've always used Castrol Edge Titanium 10w60 and it's on special now at Repco for $59 for who ever else uses it.

I snapped up a box while I had the chance.

Do you track with that oil too? What sort of temps are you getting at track if you do?

I hate this process haha lol, so boring waiting for all the oil to drain out lol, would it hurt to put some compressed air through the oil cap to push the oil down a little.

Edited by MrRx7s3

Well I've put the Penrite Racing 10 10w-40, I'm impressed, engine is as smooth if not smoother than the Royal Purple, oil pressure is better than with the Royal Purple, overall so far with a short drive I'm happy :-D.

I hate this process haha lol, so boring waiting for all the oil to drain out lol, would it hurt to put some compressed air through the oil cap to push the oil down a little.

It wouldn't hurt, it would just go out your intake....

Drink beer while it drains. Perfect excuse.

  • 2 weeks later...
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Just put in Shell Helix Ultra 5w-40. Best oil I've used for the RB25DET.

Smoother quieter idle, very smooth running and revving.

Had Penrite HPR5 5w-40 in there and that was not bad but it seems better with the Shell.

Before that had Valvoline Synpower 5w-40 which made the engine run very smoothly but the Shell seems slightly better.

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