Oil pressure question

[aw11man]

I have noticed lately that my oil pressure will sit at a certain point at say, 100kph and 3000 rpm it will be at a particlar notch on the pressure guage and maybe a little higher when engine is cooler, its a factory guage so no sure of actual psi figures.

Then if i go upto around 5000ish rpm (in like 3rd to stay within legal speed limits), and hold it there for a little while my oil pressure will drop a little and if it were for much longer than a minute or so it would probably head back towards half way where it sits when idleing which seems a bit too low for my likeing.

Then if i ease back to about 3000ish rpm the pressure will rise back up on the guage to its usual spot.

Just wondering if this is normal and if its just the engine and oil getting warmer and tolerances expanding therefore giving a lower reading for that period of time?. I dont yet have an oil cooler installed.

Or could it be the pump is on the way out and cant handle those higher rpms, not sure if it has always been like this or just that i have noticed this lately, engine is 3sge.

[IN 05 NT]

viscosity of the oil at certain temps,

cold oil will casue higher OP, say cold, 80psi at idle, warm is 45psi at idle,....(normal)

holding it at 5000rpm causes the oil to get hot, and the OP will come down a bit, (normal)

everything you have said sounds like normal operating condition,

has the oil been changed recently? and can you access the OP release valve and clean it out?

[aw11man]

Yeah i changed it the other day from 10w40motul chrono to 10w50 penrite semi synthetic, because of my move to country WA i cant find motul anywhere.

The pessure seemed to stay slightly higher under 5000rpm+ loads with the motul than with the penrite although i thought the penrite would be thicker when flogged like that being 50, it could also be that toyota gave me the larger oil filter this time.

Dont know much about the release valve, where is it located? its a redtop 3s btw.

[IN 05 NT]

i dont know the 3s that well, but id assume it would be on the front of the motor near the oil pump,

[aw11man]

I think i remember someone doing this http://www.niksula.hut.fi/~mdobruck/...iy/7/valve.htm
on here a while back.
Is this a good idea?

[JetspeedCamry]

Also, take those stock guage readings with a grain of salt. There not particularly accurate.

[GT1978]

I'd say it's probably a combination of things. Temps changing tollerances and oil visco but may also be the design of the head & block. Not all engines have sufficient oil drain holes from head back to sump and at 5000rpm for a prolonged period you're probably pumping most of your oil into the head before it can drain back to the sump. Either way, might be worth putting in a proper pressure gauge to keep an eye on it. Low oil pressure is never a fun thing.


Glen