Oil pressure... low at low idle

[JohnStra]

I'm trying to decide whether to do an overhaul. I recently cleaned my oil pan and pump pickup screen, and this dramatically improved my oil pressure problem. I'm still a little worried though because when the engine is good and hot, like after it's climbed a long grade, the pressure drops very low at idle. I've noticed that my idle RPMs drop down to about 750 when this is happening - normal operating temp idle RPMs are right at 1000. The pressure still responds fine to revving the engine, it's just real low at idle.

Suggestions? This is for a 92 Toyota V6 w/ 83k miles on it.

 

[Amkeer]

Thats normal no reason to be concerned. You will have low pressure at idle. Your idle speed is 750 which is normal also. You only have 83,000 mile on your motor it should be good for 200-300000 miles! Keep the oil changed and don't worry about it.

Daily Drives:
-2003 Toyota Tacoma PreRunner XtraCab, Impulse Red, Peppy 2.7 Liter 4 Banger, Running Mobil 1 Synthetics SS 5w30.
ODO 7100 Miles.
-1995 Toyota 4-Runner, Evergreen, 3.0 V6, Running Mobil 1 Synthetic SS 10w30.
ODO 83110 Miles. (Switching to GC next)Nope sticking with M1.
http://community.webshots.com/user/amkeer

 

[Steve S]

How low is low? Did you have the truck since new? How much sludge was there in the pan? How often did you change the oil? Install a temporary mechanical gauge to check if the eletrical sender is bad? What viscosity are you using?

 

[JohnStra]

Steve -
Low as in the OEM guage drops to almost nothing. I installed a mechanical guage and it reads 18-20 psi at the point I'm calling really low.

I bought the truck new. Took decent care of it but not great. Pretty regular 3-5k OCI. Never paid attention to oil brand though.

There was a lot of sludge. Pickup screen was almost completely blocked.

I'm now running Amsoil S2K 0W-30. I ran Amsoil's engine flush when I switched.

What do you think?

 

[Propflux01]

I think that 0w30 might be part of it, but 18-20 PSI at 750 idle is not bad.

 

[JohnStra]

I wondered about the viscosity since it only reads low when hot. It's interesting that 18-20 barely registers a reading at all on the OEM guage. I'm using a new sender so I have a high degree of confidence that it's ok. Maybe the wire or guage?