Depends, where did you tap the pressure feed. The farther from the pump you tapped it the lower the guage will read. This is based off a guage tapped into the IS300 banjo bolt holding the oil filter adaptor on.
The reason you have lower oil pressure is the sender is on the other side of the block. The oil feed lines will never see much more then 60psi input pressure, because the failure pressure for most turbo oil seals is 80psi. For a true reading you want the sender as close to the pump as possible, such as at the oil filter adaptor. Essentially the reason for a oil pressure uage is not the actual number as to enable you to establish what normal is, then you will know something is wrong when you get an abnormal reading. if you want a more accurate reading though move the sender to the oil filter adaptor using a sandwich adaptor or the IS300 bolt.
That unit is just a dummy light sender. at the filter is ALWAYS the truest reading. If you have no AC go for it, but people have had mixed results there, ive never used that method, only the lexus bolt method, because ive done it personally.
I have my oil pressure guage hooked up to the rear turbo oil feed as well. Unfortunately, I can't give you any good results yet as it seems I have a problem. I installed the guage because the oil light stayed on when I started it.
I let the engine idle for a little while and the pressure did come up to about 30-35psi but it was quite slow to get there. (This is a new engine conversion) Then when it reached operating temp it lost pressure again. So I pulled the oil inlet off the turbo and sprayed it into a container and it seems that it squirts a bit of oil and then a heap of air.
So I think that it is sucking air from the oil pickup because I have swapped from a mid sump to a front sump but I used the old o-ring and gasket. So I have ordered these parts and will swap them in and see how I go. If that doesn't work, does anyone have any ideas?
I changed the gasket on the oil pickup gasket tonight and started it up. It was on 40psi instantly! I am using 10w30 oil. I waited for it to get up to operating temp again and it stayed at around 30psi for quite a while and then went to about 20-25. The oil guage is fitted in the front turbo oil inlet.
Jewishjalopi: this is similar to how yours reads right?
I only used that because that is what is recommended by Toyota. I know that the engine is not new now. So what would you recommend? I was thinking 20w50 but that is the generic sort of stuff that normal cars use so I wasn't too sure.
When i start my car in the morning, my oil pressure jumps to 60 immediately. The oil pressure will gradually lower as the car heats up and approx. 10-15 of driving my oil pressure at 700rpm is at about 18. If i touch the gas, it immediately jumps to 35-40.
Well for a turbo charged car, every authority ive talked to and every study ive read recommend running nothing thinner then 10w40 for hot summers, and 20w50 for the rest of the time. If you like synthetic mobil1 15w50 has an additave blend that doesnt exist in their 10w40 and 20w50 blends that is quite favorable for turbo engines. If you poke around on www.bobistheoilguy.com a lot of guys are touting Delvac1 for use on turbocharged gas engines (its developed for turbo diesel truck engines and is highly resistant to ashing and coking). That site has tons of info, but i think what you will ultimately find is that thinner weights are only used to reduce engine windage losses to improve gas mileage and have little performance benifit. However do some reading before you make a decision based on my ramblings.