Lowest Oil pressure question

[akauth]

I just did an oil change to a lighter grade of synthetic 5w30 vs the 10w30 that I was running.

I also bumped up to an oil filter that was twice the factory size (an AMOIL SDF 15 vs the SDF 57 or whatever the suggested size was). That might be the larger part of my issue.

I've been running the AMSOIL SDF 57 (or whatever is the recommended size) and Mobil 1 10w30 for a while now. Been really happy with that, but still looking to do it better if better can be done.

This weekend I found that I can finally get Mobil 1 5w30 in place of the 10w30 and the price is that same at costco. So I stocked up. I didn't think it would make much of a difference. Certainly not noticable except perhaps in gas mileage, if that.

Now that I've gone with the SDF 15 which is easily twice as large as a "factory" sized filter in conjunction with the 5w30 I'm a little suprised that when I stop now (in drive) and the RPM drops to 500 rpm that the oil pressure drops to almost nothing. Barely above the lowest mark. (halfway to the next mark).

It's always be usual for the oil to drop to the second mark from a little more than the middle of the gauge.

Now it almost drops to the lowest mark. When hot and stopped at a light, the pressure drops to half way between the first (lowest mark) and the second mark. Almost hits the first mark sometimes.

I'm kind of wondering if this is mostly due to the thinner oil or if it's more likely due to the larger filter (my guess).

I'm a little worried though. If the pressure has dropped some at rest (assuming it's not from engine wear) is that a big deal?

It seems that it shouldn't matter. The oil should actually flow better now that I've put the larger filter on there even if the pressure isn't as high since it's passing through a smaller obstruction. As long as the loss isn't in the engine clearances.


Any thoughts out there? Too, what are people's lower oil pressure reading when at rest with regular oil and also with synthetic oil? What does it stay at when at highway speeds (warm engine?)

I'm wondering if maybe I should put the smaller filter back on to raise the oil pressure. Too, it may be that with the 5w30 (even though it's synthetic) that it's normal to drop to between the first and second mark. It's been so long since I've run 5w30 that I don't even remember how low it got then.

Even at high pressure at speed, I barely go over (and sometimes don't) the halfway mark of pressure.

I think I used to peak at 75% of the guage when starting and running cold or hitting highway speed. Now I'm in the middle of the guage at highway speed.

Anyway, people's feedback on their oil pressure in conjunction with the oil they are running would be appreciated.

Too, I notice a little more vibration with the lighter oil. I even double checked to my oil level to make sure that it wasn't low oil. While I had 7 quarts in, that was enough to fill it to about the halfway mark on the dipstick.

I'll see what it's like when it's cooler in the morning. It was pretty warm.

I changed the fluids in the tranfer case and the differential also to AMSOIL 75w90 from mobil 1 in the rear diff and conventional in the transfer case. That shouldn't be a source of vibration when accelerating. Wasn't there before the fluid changes.

I'll double check the fluid levels in those tomorrow morning. I wasn't on the flat and might have filled it a little above the fill hole, which should have no effect (other than to pour out a little when on the level and checking it).

Any thoughts would be appreciated.

Ooops. Just thought about it. I put in a pretty strong dose of injector cleaner in. That could be a source of the vibration. Never happened before, though. I'll have to see on the next tank.

Alan

[stylesbichly]

My readings with Mobil1 10w-30 are the same as yours with the same 10w-30. I use an OEM filter.

I can't remember what my readings were in detail when I had 5w-30, but I am sure they weren't as low as yours.

[akauth]

Originally posted by stylesbichly
My readings with Mobil1 10w-30 are the same as yours with the same 10w-30. I use an OEM filter.

I can't remember what my readings were in detail when I had 5w-30, but I am sure they weren't as low as yours.

My pressures seem a little low. I supspect it's the huge filter. Not sure if the low pressure (even lower than the OEM) lower is bad though.

Maybe one of the guys running 5w30 syn can comment on their pressures. I don't remember it being much different with 5w30 petrol based, but it's been a while.

The other thing would be - who's running an SDF 15 from AMSOIL and what is your pressure with what oils. It's a *big* filter.

alan

[SATundra]

I'm running Mobil 1 5W-30 syn, with the Mobil 1 filter (MF-102). When I changed over from the "dino" I noticed only a small, very small, drop in pressure. Like only a needles width or 2, no more. It is definately more noticeable (gauge reading) at idle for sure. But still reads above the 1/4 mark (barely) even at idle.

I would suspect the larger volume in the new filter is the culprit here, BUT what about the people running the "duel" filter setup. I would assume the volume in the duel filter setup is even more than just the single larger filter. If that were so then these people shouldn't even show ANY pressure on the gauge. Very interesting.

RagerXS and others what type of readings do you guys with the duel filter setups get?

SATundra

[stylesbichly]

This still isn't giving a direct answer to akauth's original question (sorry), but...

With a dual setup, sounds like there's no significant loss of pressure because (a) you need to add extra oil to compensate for the added capacity and (b) the design of the bypass filter is "partial flow".

http://www.amsoil.com/products/bf.html

I think the OEM filter holds almost 1/2 quart. It looks like the SDF-15 holds 2-3x that. If it's closer to 3x, then the system capacity is 1.5 quarts higher (but I think you'd notice a lower reading on the dipstick).

I went and looked up the application for the SDF filters at http://amsoil2.cpinternet.com/ and it returns SDF-57 as the recommended filter for the Tundra V8, not the SDF-15 that I have read many people use on their Tundras. The SDF-57 appears to be a smaller filter based on the price (under $10).

[rodchester]

akauth,
Right now I have Mobil1 5w-30 and a Mobil1 oil filter on my '02 V6. I have the same oil pressure readings as you are having now. The dealer says this is normal. Said as long as you're showing any pressure at all you're OK. The Tundra FAQ on this site says about the same thing.
Rod

[akauth]

Originally posted by rodchester
akauth,
Right now I have Mobil1 5w-30 and a Mobil1 oil filter on my '02 V6. I have the same oil pressure readings as you are having now. The dealer says this is normal. Said as long as you're showing any pressure at all you're OK. The Tundra FAQ on this site says about the same thing.
Rod

If it was that way since new, it wouldn't be a bid deal. But it definitely seems to have dropped a "halfmark" on the guage at high and low pressure. I'm just surprised it's that much of a drop. It must be the 5w30 that is doing it and not the larger filter.

I am wondering about the vibration though. If it doesn't go away, I'm bumping back up to the 10w30 as it did run smoother. Like I mentioned, it could be due to the injection of cleaner for the fuel system/injectors.

I know, I know. I shouldn't make a difference in the smoothness of the engine, but I am feeling a difference. The vibration is the bigger reason that I was worrying about the pressure drop. It's only a little. Unless I drove it every day though, I wouldn't notice a difference. It's extremely subtle. Road conditions create *much* more vibration.



alan

[v8Toilet]

I run Pennzoil or Mobil 1 synthetic 5W-30W motor oil in my V8 engine and the oil pressure never goes lower than just above the quarter mark with the engine fully warmed up and the transmission in drive (rpm @ 500). I have run 0W-50W by accident once for 120 miles and the oil pressure was only slightly higher than it was with the 5W-30W synthetic oil. When I realized what I had done I switched it back to the correct viscosity ASAP. I also use nothing but Toyota oil and air filters on my engine. From what I have seen most aftermarket oil filters are not up to the standards of the OEM filters even though they may say they are.

I suspect that your larger than normal size oil filter is somehow leaking pressure through the inside of that filter and if so could cause your engine harm especially if it lets unfiltered oil pass through.

There should not be any oil pressure difference between 5W-30W oil and 10W-30W oil when the engine is fully warmed up. They both act as a 30 weight oil when the engine is warmed up. The only difference between the two is that 5W-30W oil will flow better when cold than 10W-30W oil will.

5W-30W oil acts like 5-weight oil when it is cold letting the oil flow better. This lets the engine get vital oil flow when the temperatures are cold out. They both act like a straight 30 weight oil when the engine has reached engine operating temperature (usually 195-205-degrees) so that the oil doesn’t become too thin giving the engine less protection and reduced oil pressure.

My point is you should not have any difference in your oil pressure using 5w-30w or 10W-30W oil with a fully warmed up engine. Your problem is most likely that oversized oil filter. In fact why would anyone use 5w-30w oil? It has no advantage over the 10w-30w oil.

[akauth]

Originally posted by v8Toilet

I suspect that your larger than normal size oil filter is somehow leaking pressure through the inside of that filter and if so could cause your engine harm especially if it lets unfiltered oil pass through.

There should not be any oil pressure difference between 5W-30W oil and 10W-30W oil when the engine is fully warmed up. They both act as a 30 weight oil when the engine is warmed up. The only difference between the two is that 5W-30W oil will flow better when cold than 10W-30W oil will.

.....In fact why would anyone use 5w-30w oil? It has no advantage over the 10w-30w oil.

I'm guessing that the issue is the filter if most people seeing the same pressures with 5w30 as 10w30 synthetic. It's not a quality issue with the filter or "leakage" past media though.

Because the area is so much larger than a factory filter (or replacement), there is a *lot* less resistance through the filter. The pressure has to drop since the capicity to filter has been increased so much.

My question has two parts. One) what are people seeing for pressures? Two) Is a larger filter which is going to cause less resistance to the overall system necessarily a bad thing?

I don't know. Maybe George has an answer to that.

In going with the larger filter, I've probably tripled my capacity for carry dirt (maybe quadrupled). I know that I've at least doubled it at least.

I'm using the lighter oil to see if I can get a gas mileage increase. If not, I'm going back to 10w30 which will work anywhere in the lower 48 at any time of year.


Alan

[v8Toilet]

Originally posted by akauth


I'm guessing that the issue is the filter if most people seeing the same pressures with 5w30 as 10w30 synthetic. It's not a quality issue with the filter or "leakage" past media though.

Because the area is so much larger than a factory filter (or replacement), there is a *lot* less resistance through the filter. The pressure has to drop since the capicity to filter has been increased so much.

My question has two parts. One) what are people seeing for pressures? Two) Is a larger filter which is going to cause less resistance to the overall system necessarily a bad thing?

I don't know. Maybe George has an answer to that.

In going with the larger filter, I've probably tripled my capacity for carry dirt (maybe quadrupled). I know that I've at least doubled it at least.

I'm using the lighter oil to see if I can get a gas mileage increase. If not, I'm going back to 10w30 which will work anywhere in the lower 48 at any time of year.


Alan

The oil pump working against the clearances in the engine bearings makes the resistance that builds oil pressure. Most oil gauges read oil pressure after the oil filter.

I would say you are playing the bigger is better Tim Allen game with your $5000+ engine and taking a risk. Toyota engineers designed the Toyota oil filter to be a certain size with a certain filter design to protect the engine and work with the rest of the oiling system as just that an oiling system. That is something that you should not mess around with in a 20-30k truck.

When I was rebuilding engines the rule of thumb was 10 PSI for every 1000 RPM of the engine. Just because your oil filter is bigger and may allow more volume to get by does not mean oil pressure will drop. It shouldn't drop! Aftermarket oil companies don’t make oil filters that drop your oil pressure, if they did they wouldn’t be in business very long! When I had a GM car with the 2.8-liter engine I remember there was two types of oil filters that I could use in that engine, one was very small and one was very large. I had used both and they did not make a difference in my oil pressure. That engine always had 22 PSI of oil pressure at an idle. I didn't know what filter for the 2.8-liter engine was the correct one nor did I care since the car was just a cheap beater POS car.

There is also a difference between oil volume and oil pressure. I have taken an engine that had 20 PSI of oil pressure at idle with a stock oil pump and added a high volume oil pump and ended up with the same oil pressure but just more oil volume reaching the engine. To increase the oil pressure I had to install a stiffer spring in the oil bypass valve.

I had started a thread in this forum a few weeks ago concerned that my oil pressure was abnormally low. Other members here replied that the needle just above the quarter mark is what they had also and that was normal.

[airplanegeek]

Howdy, my two cents on oil. Adding larger filter, thinner oil, etc lowered the oil pressure 'cause the bearings have clearances that allow the thinner oil to flow faster. Fast enough that the pump does not see enough resistance to reach 'regulated pressure'; whatever the pump pressure relief valve allows. The pump pumps, the bearings use, and oil pressure readings reflect the relationship between them. Try the new oil with the 'before' filter, take notes. By changing one variable at a time, you can nail down what is happening in Your engine. If the larger filter causes lower pressure, the older filter was a significant restriction, and the bearings may have suffered. The oil passages have not changed. This very much depends on where the psi gauge taps into the system.
Cheers.