Low oil pressure with switch to mobil 1

7314 Views 17 Replies 10 Participants Last post by wjdunn3, Dec 26, 2005

gibbsjo

Discussion Starter · Dec 22, 2005

I did my second oil change at 4,500 miles switching from dino oil to mobil 1 and my oil pressure at idle is really low. At operating temp with dino oil my guage read 25 now with mobil 1 (both 5W30) it reads 12-13. Is this normal? It reads around 60 at cold start up same as before and around 45-50 at cruising speed same as before. Its an 05 with the 4.0 motor. The gauge is an autometer with electric sending unit. Just curious if anyone has experience the same thing. Also the tick is definately louder now when the engine is warm I presume due to decreased oil pressure.

Thanks,
Jon

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Tacologist

· #2 · Dec 22, 2005

Mobil 1, although a true 5W-30 tends to be on the thin side of the scale. As a result, oil pressure will be lower with a thinner oil than with a thicker grade. Look what happens when oil gets hot and thins out accordingly, oil pressure goes down.

This also may contribute to the louder valve noise. There is less dampening effect with the lighter oil. I have heard this mentioned on BTOG (Bob's the Oil Guy) site where oil is discussed intimately.

I currently have a blend of Mobil 1 5W-30 and Mobil Clean 5000 in my 4.0 engine at 4000 miles and don't notice a sever ticking. My next change will be pure Mobil 1 and a new evaluation will take place at that time.

My service manager said that Toyota does not endorse synthetic oil. This does not mean it says you shouldn't use it, just that they have not put in writing that you should use it. I think they are concerned with 12-15000 mile oil changes that, as we know, are taboo in for the warranty. They may be a bit gun shy because of the sludge problem they faced some time ago in the smaller V-6 engines they had.

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gibbsjo

Discussion Starter · #3 · Dec 22, 2005

thanks that what I thought, but 12-13 psi at warm idle really scares me.

grnmt4x4

· #4 · Dec 22, 2005

I don't know if this helps but I use Mobil 1 5W30 synthetic and have a K&N oil filter - no ticking sound. I am in Vermont and it was 5 below this am so I am more concerned about oil getting circulated quickly on start up. No problems this summer though either - have 12k on the truck.

dorkman

· #5 · Dec 22, 2005 (Edited)

What oil filter? I have the same gauge and I run Mobil 1 with Toyota filter, on start up it runs the same as with Dino, right at almost 75 on the gauge. At Idle when warm it runs 25 and at 2K RPMs running 70MPH it seems to be around 50 on the gauge.

Now like others have said, this is not the crank case pressure since the sensor is right next to the filter.

I think its your filter choice not the oil. I used a Mobil filter once and it ran about 5 PSI lower on startup since it was a high flow filter. But tick or no tick I have noticed NO difference with oil or filter combinations, mine does not have a tick that I find abnormal for any engine.

Do you still have the idiot light hooked up? If that does not go off I am sure your fine.

Edit: Also of course check your oil level, make sure your not low....sure you already have but you never know. I would check your oil level, if thats OK I would stick a Toyota Filter on there and see what your PSI changes to.

gibbsjo

Discussion Starter · #6 · Dec 22, 2005

its a mobil 1 oil filter and I still have the factory idiot light hooked up. I used a mobil 1 filter with the dino oil on the first oil change as well. Maybe I'll try the toyota oil filter. Thanks

57HotrodVW

· #7 · Dec 22, 2005

I believe that the generally accepted/suggested oil pressure minimum is ~10 PSI per 1000 RPM.

--Eric

wjdunn3

· #8 · Dec 22, 2005 (Edited)

12/13 psi at idle (600-700rpm?) is not bad. The idiot lights generally do not come on until 5 - 7 psi. I could not find quickly what the min oil pressure for the Tacoma was but I will look more this evening.
What is the prerssure at: 1000rpm; 1500rpm and 2000rpm?

If you do not live in a cold climate (where it doesn't get below 32deg) then you could move to a 5w-40 which would help the pressure at idle.
[EDIT] - I see that you are in CT so during the winter a 5w-40 may not be a good idea.
57HotrodVW's stmt above is a good general rule of thumb to go by.

DaleClough

· #9 · Dec 22, 2005

Oil gauge? Am I missing something? Thought the only offering was idiot light.

dorkman

· #10 · Dec 22, 2005 (Edited)

You mean you did not get a factory Oil pressure gauge? I would go back to the Dealer and complain.

gibbsjo said:
The gauge is an autometer with electric sending unit.

Not missing anything, its aftermarket gauge with the idiot light still hooked up via a T adapter probably like I did mine.

Edit: If you want to add some gauges read here to get you started

http://toyotanation.com/forum/t110917.html

Tried2Live

· #11 · Dec 22, 2005

57HotrodVW said:
I believe that the generally accepted/suggested oil pressure minimum is ~10 PSI per 1000 RPM.

--Eric

:thumbsup:

It's probably not that big of a deal. The oil pressure in my Mustang is only at about 10-15 lbs at idle and that's with 15W-50 Mobil 1. When I got the shortblock, they said they left the clearances a little on the loose side, but as long as I ran 50-weight oil, and the pressure was over 10 pounds per 1000 RPMs it would be fine. I've had the motor in there for almost 3 years now with no rebuild, so I'd say it's doing fine. (I'm far from easy on that car too.)

gibbsjo

Discussion Starter · #12 · Dec 22, 2005

oil pressure at 1000 rpm is 25, 1500 is around 40 and 2000 is just below 50. This all seems normal based on previous experience. My friend has a 2000 v8 tundra with the factory gauge and at warm idle it sits just below the L for low. Based on that all seems normal but I may change the filter and see if it changes.

DaleClough

· #13 · Dec 22, 2005

dorkman said:
You mean you did not get a factory Oil pressure gauge? I would go back to the Dealer and complain.

Not missing anything, its aftermarket gauge with the idiot light still hooked up via a T adapter probably like I did mine.

Edit: If you want to add some gauges read here to get you started

http://toyotanation.com/forum/t110917.html

Gotcha, thanks!

wjdunn3

· #14 · Dec 22, 2005

gibbsjo - your oil pressuer at 1000 is great:thumbup: . I would not worry about the idle pressure unless the idiot light starts coming on. Putting a more restrictive oil filter on is not going to help. Yes, the gauge may read a little higher but you are only hurting flow down stream where it really counts. Stick with a high flow filter. If you are still worried you can try the 5w-40 or a 10w-30 as long as you don't leave you car outside overnight regularly during the winter and don't jazz the gas pedal until the engine is up to temp.

gibbsjo

Discussion Starter · #15 · Dec 22, 2005

thanks guys I feel better now, so for what it is worth dino oil provides more oil pressure at idle than mobil 1 of the same weight. I guess synthetic oil is alittle thinner.

Rotorwrench

· #16 · Dec 26, 2005

The service manual states, minimum oil pressure at idle- more than 4.3 PSI. At 3000 RPM 45-85 PSI.

R0dzilla7

· #17 · Dec 26, 2005

This is a little off topic but I have a question about how the oil filter is situated. Isn't it bad for the engine to have the oil filter set so that the oil has to be pumped into it before it gets to the engine? I mean when you go to start your vehicle doesn't it pull from the filter first? And if it does and the filter is upside down it isn't getting anything for a small amount of time? Just curious.....this probably sounds like a stupid question to those who know more than I do about engines. Thanks

wjdunn3

· #18 · Dec 26, 2005 (Edited)

No, the oil is not "pulled" anyplace except out of the oil pan. It is pushed from the oil pump through the filter and into the rest of the engine (main oil galley, etc). The oil should always be filtered before entering the engine.

If oil was pulled, then you would not have oil pressure, you would have oil vacuum. :lol: Sounds strange doesn't it!

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