Interesting Oil Pressure Info - Toyota Nation Forum : Toyota Car and Truck Forums

***Mister_Perkins*** · 02-09-2011, 05:28 PM

Previously had 10w30 in my car until my last oil change.

I decided this time I would go with 5w30 Non-Synthetic this time around.

Interesting developments (Normal Operating Temperature)

10w30 at idle around 5 Psi
3000 RPM around 40 PSi

5w30 at idle around 20PSi
3000 RPM around 55 PSi

I don't know if it was just switching from 3000 mile oil to new oil that gave me a around a 15 PSi at idle difference, but I think from now on I am going to run 5w30 in all the camrys.

I am uploading a video of the pressure difference, but I just thought you guys would be interested in the results

Edit: Video

You Tube

carsrus · 02-09-2011, 06:51 PM

The age of the oil wont affect psi.

Honestly, those results make no sense. I have no idea why that would happen. Once oil is at operating temp. the Winter number doesnt play a role. It just acts as a 30W oil.

56 psi at 3k rpm is pretty high too.

***Mister_Perkins*** · 02-09-2011, 06:55 PM

Quote:

Originally Posted by carsrus

The age of the oil wont affect psi.

Honestly, those results make no sense. I have no idea why that would happen. Once oil is at operating temp. the Winter number doesnt play a role. It just acts as a 30W oil.

56 psi at 3k rpm is pretty high too.

From Repair Manual

Oil pressure:
At idle
29 kPa (0.3 kgf/cm, 4.3 psi) or more
At 3,000 rpm
245 – 490 kPa (2.5 – 5.0 kg f/cm, 36 – 71 psi)

Im pretty sure that the oil pressure difference is due to oil level difference. Between the changes, the oil pressure was about 1/4" below full, and when I changed it, i filled it right to Full.

Chris Crash · 02-09-2011, 06:57 PM

56 psi at 3k is fine. The range is stupid... like 12-72 psi at that RPM.

At idle normal is 4-50 something.

I feel like that's such a terrible range.

***Mister_Perkins*** · 02-09-2011, 07:01 PM

lol, I totally agree.

I guess it really doesn't matter though as long as its 4 or more at idle, and more than 36 at 3000. Wonder what the Psi would be if I shimmed my relief valve

agni · 02-10-2011, 12:05 PM

Yea that is interesting. A lower viscosity means less resistance to flow, so the backpressure should be lower. Normal oil loses viscosity more readily as it ages and breaks down, so if your old oil was starting to break down that could explain it. It kind of sounds like you were using synthetic previously though?

***Mister_Perkins*** · 02-10-2011, 01:23 PM

No , It was just a different Viscosity.

it was BradPenn 10w30 Regular

Stillrunning · 02-10-2011, 03:11 PM

Cannot compare dirty oil with clean oil of different grades and expect to assume anything. It may be that your old oil was contaminated with fuel that lowered it's viscosity, or that the oil pressure is taken upstream of the oil filter and a dirty filter caused a pressure drop. Oil level in the pan won't affect pressure as long as the pickup tube is sucking oil not air. I'd get a used oil analysis to see what if any contaminates are in the oil.

***Mister_Perkins*** · 02-10-2011, 03:16 PM

eh, I'm good .. I just thought it was nice to see my pressure was higher than last time. Thanks for the information though

And btw, I wasn't assuming anything. I have had the oil pressure gauge installed for a long time. In that time I've monitored the oil pressure with 10w30. Now I have 5w30 and monitored it. Its a Mechanical gauge that is Tee'd off at the Oil pressure sensor on the head.

My filter was not very dirty .. I actually cut it in half and inspected it. Theres a video posted up on 3rd/4th gen camry. I doubt that my oil has fuel in it as the motor runs excellent, has Almost OEM Spec compression, no oil leaks, etc.. (motor has under 100k on it).

Again, thanks for your incite on what you think was the cause.

If you would like some good reading, check out:

http://lubricants.s5.com/oil_pressure.htm

Stillrunning · 02-10-2011, 05:48 PM

Quote:

Originally Posted by Mister_Perkins

I doubt that my oil has fuel in it as the motor runs excellent, has Almost OEM Spec compression, no oil leaks, etc.. (motor has under 100k on it).

I had similar condition on a Montero but an oil analysis showed excess fuel in the oil. I sent the injectors out for spray analysis/cleaning. The next analysis came with with 0% fuel in oil. It can be as little as a leaky injector. Anyone interested in keeping track of their engine should do an occasional oil analysis.

***Mister_Perkins*** · 02-10-2011, 05:51 PM

Quote:

Originally Posted by Stillrunning

I had similar condition on a Montero but an oil analysis showed excess fuel in the oil. I sent the injectors out for spray analysis/cleaning. The next analysis came with with 0% fuel in oil. It can be as little as a leaky injector. Anyone interested in keeping track of their engine should do an occasional oil analysis.

hmm interesting to know. Thanks

doozergreengrass · 02-11-2011, 07:58 PM

Quote:

I had similar condition on a Montero but an oil analysis showed excess fuel in the oil. I sent the injectors out for spray analysis/cleaning. The next analysis came with with 0% fuel in oil. It can be as little as a leaky injector. Anyone interested in keeping track of their engine should do an occasional oil analysis.

Is it usually bad injectors that cause this? I've only had my Camry 16 months, and i've done more than its fair share of oil changes in that time (probably up to about 4th change now). Since having it its old oil has always smelled like fuel. I think its running rich-it smells like it from the exhaust. would this cause the same thing? Also, do clogged/blocked innectors make a ticking noise? I always thought my ticking was from under the v/c, but maybe not....

Interesting results with the oil pressure, I wish every car had an oil pressure gauge, isn't it vital and more reliable than a light that only comes on at (4psi?) How useless is that!

***Mister_Perkins*** · 02-11-2011, 08:08 PM

An O2 sensor reading incorrectly can cause the ecu to over compensate and enrichen the fuel mixture. Most of the time it throws a code though. If your car is running really rich, its actually bad because you could be getting a lot of gas dumped into the cylinders and wash your rings out

Go to your parts store and find a Noid light and test to make sure all the injectors are pulsing at the same interval too. You can also check the resistance of the injectors. Its always a good idear to get them cleaned every once in a while

doozergreengrass · 02-11-2011, 08:29 PM

Ok thanks Mister Perkins. Well I have a digital multimeter so i'll search now on how to test them out. I recall some interesting injector info in a thread I think by fenixus, so i'll look all that up now, including whether they can make a ticking noise (though, I expect its something to do with the valves - but if thats the case why, the valves have supposedly been 'fixed').

Btw, i'm currently running Castrol GTX Modern Engine 10w-30. I'm not sure if its dino or a blend, it doesn't say. Anyhow its whats in there til my next change, i'm hesitant to put the best oil I can afford in there until all my issues are solved, and as I said earlier the vehicle has had more than enough filter/oil changes in the last 16 monts. I change out the filter every time too, as I don't really see any point leaving an old one in there and only changing oil like some ppl prefer.

***Mister_Perkins*** · 02-11-2011, 08:32 PM

If you have a piece of wood that is flat on both side (large dowel rod or cut broom handle works) Place it against the injector and put it up to your ear. Works similar to a Stethoscope and you can hear if the injector is tick tick tickin'

Other causes could be a leaking injector, bad fuel pressure regulator, Coolant temp switch for computer (not gauge), exhaust leak before the O2, Cracked vacuum line / broken vacuum / disconnected vacuum, incorrect TPS reading can also trick the computer into over compensating the fuel mixture.