Low oil pressure with dino?

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Jimmy9190

Jimmy9190

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I used Maxlife 10w30 and a Purolator Premium Plus filter for my last 4 oil changes and the oil pressure gauge always read right at 3/4 on its scale when cruisng about 75 mph at 2000 rpm. Now on my most recent oci I used 10w30 Valvoline dino and an AAP Total Grip filter, because they were on such a good sale. Now the oil pressure reads lower, between half and 3/4 at cruising speed and rpm. Is this because the dino is thinner at that operating temperature and speed? I know the Maxlife is thicker and is a syn blend with a high mileage add pack to it. Engine has 83,000 miles on it and runs fine, but which oil and level of oil pressure is better?

Any help is greatly appreciated...
 
What is the vehicle. Many Fords from the 90s on up have dummy oil pressure gauges that are really no more than a needle instead of an idiot light. With such a gauge, the needle will tend to vary for some reason, but it is meaningless unless it goes all the way to the left. A real oil pressure gauge should show a lower reading at idle and the needle should raise when the RPMs increase, but will level off at some point, maybe around 2000 or so RPM due to the pressure relief valve in the pump. If both oils are rated the same cSt at 100C (and those two should be close enough) you should not get a significant variation in oil pressure.
 
I would stick with the Maxlife for the future, not that Valvoline conventional is bad, just not as good as Maxlife in several areas. Better base stock, additives, etc. Valvoline as much as admits the quality difference on their website if you read a while. I think that the Maxlife will help in keeping engine internals clean, fuel economy due to moly, and safely extended oci to 5k or more depending on how driven. AA filter is a good filter considering the half price sales. I use them without concern.
 
Thanks. My truck is a 2001 Dodge Dakota 3.9 v6 with a 5speed manual. It has gauges in the dash for the battery, temperature and the oil pressure, but I don't think they operate the same as a traditional mechanical gauge. The battery gauge is really an ammeter, not a true voltage gauge, and the temp and oil pressure gauges get their input from the PCM, not straight from their respective sending units. So I don't know whether to really trust their readings. The oil pressure needle does read lower at idle and sweep across and stop when I reach cruising speeds, but since this last OCI the needle also seems to sweep back down faster when the RPMs drop, as in when slowing down to stop.

I agree with what you all have said, and I appreciate your help. I used the conventional Valvoline this time because it was on sale for a good price at the time. I even bought 5 more jugs for my stash because it was half the price of a 4 qt. jug of Maxlife. I think I'll keep the AAP filters I have stashed but I am going to try to return the dino oil and exchange it for Maxlife. I'll go ahead and change the oil and filter again this weekend too. I never had a problem like this before, and if the gauge still reads wrong I'll change out the sending unit next. Or maybe find out how to replace it and the ammeter with regular mechanical gauges without throwing off the signals to the PCM. If anyone knows about that, I'm all ears.

Thanks again everybody,
 
Oil pressure input from the PCM. Seems there was a thread about this, a simulated oil pressure gauge or something like that. More devious than the Ford dummy gauge I guess. Can't figure what the worth of it is though. Guess you should just not worry about it unless you are an oilhead enough to install a real gauge.
 
Thanks again. I am going to research the possibility of adding both a mechanical oil pressure gauge and a regular voltmeter gauge. If I can do it without sending my PCM into a hissy fit, I will. I take really good care of my truck and knowing what is going on with my engine and the ability to accurately monitor what is happening with it is critical to me. Will try to post what I come up with.
 
Thanks for the help. Oil pressure gauge seems to be working right again. I will take off the connector and make sure it's all clean but other than that I'm going to leave well enough alone for now. Truck has been fine with its original battery gauge too, so will probably not add any volt gauge either.

Thanks again,
 
I use purolator premium plus because I get a higher oil reading of 3-4 psi over fram, wix, or super tech. I like the higher oil reading but doubt it means anything.
 
According to SVT above the higher pressure would mean less flow than your other filters.
 
Originally Posted By: Jimmy9190
Thanks for the help. Oil pressure gauge seems to be working right again. I will take off the connector and make sure it's all clean but other than that I'm going to leave well enough alone for now. Truck has been fine with its original battery gauge too, so will probably not add any volt gauge either.

Thanks again,


If the oil sending unit on a Ford that uses a pressure gauge is removed for any reason and wrapped with Teflon tape, it will read lower than w/o the tape. I made this discovery, and then read about it about a year later, after I installed a pre-luber. IIRC it has something to do with how the unit is grounded.

Frank D
 
Which side of the oil filter is the sensor measuring the pressure of the oil flow: the input side or the output side? This would help in the conflicting opinions regarding filters, weights, and base oil groups.
 
Thanks again for the help here. I don't know which side the sensor gets the measurements from. I may be able to tell when I get under the truck tomorrow. I am going to change the dino out for Maxlife, as long as AAP lets me exchange it. The AAP filter is made by Purolator and has slightly less filtering media but is it enough of a difference to have that much effect on the oil pressure gauge? That may be a good question to send to Purolator. Oil pressure was reading a little low again today on the way to work. It's still well within the "normal" range on the gauge but I wonder what exactly is happening here. I got a few more MPG with Maxlife before as well. Should have just kept using it instead of trying to save a few bucks.
 
Use the oil that gives you the best mpg. That's cheaper than saving a few bucks on the oil. Just my .02.
 
Originally Posted By: FordSVT
More Pressure = Less Flow

More Flow = Less Pressure
More pressure = less flow only if the pump is bypassing some oil through its pressure relief valve. With an ideal positive displacement oil pump (that’s not operating in pressure relief), the flow will be the same regardless of the system pressure.

Changes in system pressure aren’t always a result of changes in flow. Oil viscosity (and of course oil temp), and oil filter characteristics can alter the observed system pressure even without changes in flow.

All that being said, it’s possible that the oil pump could be in pressure relief under the conditions specified (2000 rpm). If that’s the case, more pressure = less flow. But the only way to know for sure if the flow has changed is to measure flow. Even if the characteristics of the pump and pressure relief valve are known (which they usually aren’t), it might still prove difficult to determine how much flow has changed by measuring changes in system pressure.
 
Interesting web page there, Bustednutz. AAP was good enough to exchange the dino for Maxlife today, so I changed out the dino for Maxlife 10w30 and put on a new AAP filter. The high side is still slightly lower than what I remember with the Purolator PP filter, but the pressure is reading correctly on the low end at idle. At rpm ranges in between idle and cruise the gauge responds like it should, maybe even a little more quickly than it did with Purolator filters, maybe I just never noticed. The gauge seems to be accurate, and all I can attribute the change to is that with less media than the PP filter, the AAP filter flows a little better than the PP, thus the reduction in gauge indication at cruising speeds. Or like Brian pointed out earlier, the filter itself could be affecting the reading on my gauge.

I also bought a new oil pressure sending unit at AAP today but I am going to return it and leave the OE sensor in place and leave well enough alone for now. The truck is running better and idling smoother, just as it always did on Maxlife. As long as they keep making it, I'll keep using Maxlife. It works very well for me.

Thanks for all the help here.
 
I have always loved Valvoline products. There standard conventional is a great dino oil to use. I got their SYNPower today at a buy one get one free offer.
I wish my cars had oil pressure gauges.
I'm also a big believer in the purolator filters as well.

How many PSI's can an oil filter handle before the bypass kicks in?
 
An update here..I don't get out on the interstate very much but I had the opportunity yesterday and when running 75 to 80 mph at about 2100 rpm, my oil pressure gauge was reading a little higher than it did at that speed with the Purolator filter. It was right on the 3/4 mark. There are no numbers on the gauge, only hash marks at 1/4 and 3/4. The low side at idle still reads correctly when the engine is at operating temp and it takes about half the time now for the engine to build full oil pressure on a cold start.

These things tell me that the AAP filter is a better-flowing filter and I think it may be a little more beneficial for my truck with 83,000 miles. Any ideas are appreciated here..
 
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