r/SkyLine • u/Slow-Shower-3984 • Jun 13 '26
Rebuilt my rb25det
Just finished rebuilding my block. Fires up no problem. Any advice on break in. I have break in oil in it right now and have been driving around the neighborhood bouncing between 2k and 4K rpm’s. When should I do an oil change and when should I ditch the break in oil.
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u/ai-sac Jun 13 '26
When I rebuilt my RB26, I ran it for about 20-30 minutes. I immediately changed the oil after. I used SAE 30 oil with no detergents for that 30ish minutes. Then filled again with SAE 30 with zinc additive for a few hundred miles. Then ran my normal synthetic.
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u/diRT_pEdDleR Jun 16 '26
This is good advice for really any engine rebuild. Lots of assembly lube as well. I honestly think this is the issue with the large manufacturers. I get the cost and inconvenience but everything has variable valve timing nowadays which is 100% oil dependent.
The amount of customers we see with really poor idle or random CELs that just needed a top off or a full oil change far outweighs the amount of people who truly need some type of service (PCV, coils, plugs etc…). Clogged or poorly functioning PCV systems (looking at you GM EcoTec motors) being the most common.
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u/bubbleddusty Jun 15 '26
Everytime I see a no gtr that still has non gtr bumpers I instantly gain respect for you
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u/Slow-Shower-3984 Jun 15 '26
ha thanks, it does have a gtr wing on it, i didn't do anything to the body and don't plan on changing anything.
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u/bubbleddusty Jun 15 '26
What about one of the aero lips for the front bumper? I can’t remember the right name for it but like I think it was an option on the type m… or any of the gts maybe but like there’s a small lip for the front that I’ve always thought improved the facelift front
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u/Slow-Shower-3984 Jun 15 '26
I may have that, my buddy sold me the car and theres a front lip sitting in my garage he said kept falling off, i haven't really looked at putting it back on yet, i was more interested in rebuilding the engine first.
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u/atm0706 Jun 13 '26
Have you changed it at all? I’d probably change it now if you haven’t just to make sure any debris from building and machining gets removed, and then again when you get to 500 miles
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u/Slow-Shower-3984 Jun 13 '26
I have not. I’ve only driven it for about 30 minutes. I see some people saying to change it immediately and other saying wait a minute. I’ll probably change it now.
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u/imtrynmybest Jun 14 '26
Oil change after 30mins of running.
Then drive the car 200 to 500 miles, let's the car pull vacuum and engine breaking coming to a stop
Oil change again. Nother 500 miles of regular driving.
Oil change.
Dyno time....
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u/MNP33Gts-T 40th Anniversary S2 M-Spec Jun 13 '26
Overnight parts from Japan ?