I've always heard to run 5-30 in a new/rebuilt engine. My engine has about 100 miles on it now. When I start it up it has like 50 psi oil pressure at idle. Once it gets warmed up it goes to about 20 psi. But after it has been running for a while, and when it's hot outside, the pressure drops to about 12 at idle. I realize this isn't dangerously low, but it still makes me nervous. Is the 5-30 the reason the pressure drops so low? Should I not be running such a thin oil when it's this hot outside? I don't think the problem is mechanical, as everything was within specs when I built it. What do you guys think? Should I put 10-30 in it instead?

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91 Z28
Come see The Vicious...

 

running 5-w30 in it is fine.. in fact 5w30 is recommended by most manufacturers. make sure the oil comes all the way to the top of the cross hatches on the dipstick.. it should be approx 5.25 quarts.. not 5.

 

I'm running 5w30 maxlife (Valvoline) in my car right now and it gets to 92 degrees outside...no problems yet, been running it for a while now. (need to get rid of the case of oil)

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR
-Gutted Air Boxes

 

when i build an engine i fill it with straight 30w and change the oil after about 30 or 45 minutes running time, refill it with straight 30w again and run it to around 500 miles then run what ever multi weight oil i prefer and after 4000 or so miles go to synthetic if i want. trouble is most of the engine i build aren't for me a nd i have no control over how the owner treats them or what he runs in them. a lot of people have brought me their oil to put in a new engine, i tell them what i ithnk and they usually want me to use their oil.

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM