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Thread: Oil pressure

  1. #1
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    Oil pressure

    So want to know if the following is ok or a sign of impending trouble (read money outlay).

    Brought the '64 Avanti in for a LOF.........which was realized by the installation of Shell 10/20/30 oil plus (a small bottle of Rislone ZDDP additive) and my standard oil filter that I have used continuously since 1966...(Hastings filter # LF212)
    Which is amazingly still made in the United States.:-)
    More to the point, I then drove on the expressway and noticed that the oil pressure gauge showed apx 35 pounds at between 50-60MPH........at idle looked to be about 15 pounds.
    Are these numbers indicative of impending failure to the engine?

    I just do not know if these numbers should or would be considered good for my engine?

    Thanks in advance for your combined thoughts;-)

  2. #2
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    First, a few questions?

    1. How many miles on the engine?

    2. Any signs of smoke/blow back?

    3. What type of driving do you do? How often?

    My initial view is that you need a higher viscosity oil but others may have other suggestions. Another is that at speed, the pressure should exceed that of the pressure relief trigger point.

  3. #3
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    The car has apx 110K miles on her. The car does not smoke and there is zero blow back The car is now just a "hobby' car, being used maybe 500 miles per year. The only reason I went with the Shell oil is because that is the oil that was readily available to me with out having to wait for the WD to bring over different oil. I usually utilize 20W/50 VR-1 oil, and come to think of it the pressure is always slightly higher.
    Quote Originally Posted by GrumpyOne View Post
    First, a few questions?

    1. How many miles on the engine?

    2. Any signs of smoke/blow back?

    3. What type of driving do you do? How often?

    My initial view is that you need a higher viscosity oil but others may have other suggestions. Another is that at speed, the pressure should exceed that of the pressure relief trigger point.

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    I'd go back to the 20w/50 VR-1

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    President Member Ron Dame's Avatar
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    There are many possibilities for low pressure, including a stuck pressure relief valve. But first verify you have low pressure with another gauge.

    What was the pressure before you changed the oil?

    In my case, my R2 sat for nearly 20 years with old oil in the crankcase, and the acid in the dirty oil ate the the bearings down to copper.
    Ron Dame
    '63 Champ

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    That is not bad oil pressure at all. A mechanic freind once told me it is not so much about pressure as it is about flow. I'm convinced that 30 wt oil in 1964 was thicker than the stuff you buy today. I've always said multiweight oils eg 10w40. meant they were 40 wt cold and 10 wt hot. I Agree; go with 20w50 Valvolene VR-1 and enjoy your car! I've never heard of dirty oil eating the babbit metal off of bearings; I would guess it was parked 20 yrs ago cause the bearings were worn out.

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    Quote Originally Posted by Jeffry Cassel View Post
    . I'm convinced that 30 wt oil in 1964 was thicker than the stuff you buy today. I've always said multiweight oils eg 10w40. meant they were 40 wt cold and 10 wt hot..
    Nonsense....

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    Quote Originally Posted by Mrs K Corbin View Post
    I'd go back to the 20w/50 VR-1

    Agree totally...

    Also based on consumption I could consider the synthetic version based on the mileage and frequency of driving the car which appears to have been almost regular usage.

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    The book says oil pressure should be 30 psi. I assume that is hot at idle. Mine runs around 27 under those conditions ,but I run 20-50.

    What is LOF and WD?

  10. #10
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    It sounds like this Avanti will be fine until the day the Cam Bearings wear the rest of the way out, and you see 0 to 5 Lbs.

    OR, if you plan on running it several more thousand miles, you rebuild the Engine before it's too late.

    Back in 1990, I did not overhaul my 289 in a Wagonaire soon enough, but I got lucky.
    I shut it down right away and was able to replace the wiped-out Cam Brgs., Std. Rings, Mains and -002 Rod Brgs. with no Crank damage!


    WD MAY be: Warehouse Distributor.

    LOF IS: Lube/Oil Filter.
    StudeRich
    Second Generation Stude Driver,
    Proud '54 Starliner Owner




  11. #11
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    LOF= lube oil and filter......WD stands for warehouse distributor.
    Quote Originally Posted by bensherb View Post
    The book says oil pressure should be 30 psi. I assume that is hot at idle. Mine runs around 27 under those conditions ,but I run 20-50.

    What is LOF and WD?

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    Hate to drain out the new 10/20/30 Shell oil..............if a can of STP is added, will the hot idle number increase?

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    President Member 345 DeSoto's Avatar
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    Yes, it will increase oil pressure a bit...

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    I'm not sure what oil pressure tells you. Yes, you can put heavier oil in it, and the gauge pressure will come up, but so what? That higher pressure just means that the oil is circulating more slowly.

    Actually, I think that an "idiot light" which comes on when the oil pressure is abnormally low, is just fine.

    When the new Lotus V8 was introduced many years ago, the oil pressure gauge was marked L-N-H because Lotus figured owners would panic if they knew the actual oil pressure, which was about 5 psi.

    If you think about it, the instantaneous pressure on rod and main bearings is at least several hundred psi, and on cam surfaces can be several thousand psi, so the oil pump pressure is almost meaningless. As long as oil is present, it is the oil film strength, not pump pressure which prevents metal-to-metal contact.

    Abnormally low oil pressure can tell you that there's wear and increased clearances, but it does not indicate inadequate lubrication.

    Yes, you can increase gauge pressure with thicker oil, but that does not equate to better lubrication.
    Last edited by jnormanh; 05-19-2019 at 07:14 AM.

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    President Member 62champ's Avatar
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    Quote Originally Posted by jnormanh View Post
    Actually, I think that an "idiot light" which comes on when the oil pressure is abnormally low, is just fine.

    When the new Lotus V8 was introduced many years ago, the oil pressure gauge was marked L-N-H because Lotus figured owners would panic if they knew the actual oil pressure, which was about 5 psi.
    This reminded me of a co-worker who was a big three dealer mechanic. He said the analog gauges in new vehicles today are idiot gauges. When the motor starts, the oil pressure gauge goes up and the needle stays where the computer tells it to when the oil pressure is in its normal range. He said if it showed the actual oil pressure, people would be constantly bringing in their vehicles saying there is something wrong because when they stop at an intersection the oil pressure goes to the bottom end of its range.

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    Always know I am sure to get educated from this group:-)
    Quote Originally Posted by jnormanh View Post
    I'm not sure what oil pressure tells you. Yes, you can put heavier oil in it, and the gauge pressure will come up, but so what? That higher pressure just means that the oil is circulating more slowly.

    Actually, I think that an "idiot light" which comes on when the oil pressure is abnormally low, is just fine.

    When the new Lotus V8 was introduced many years ago, the oil pressure gauge was marked L-N-H because Lotus figured owners would panic if they knew the actual oil pressure, which was about 5 psi.

    If you think about it, the instantaneous pressure on rod and main bearings is at least several hundred psi, and on cam surfaces can be several thousand psi, so the oil pump pressure is almost meaningless. As long as oil is present, it is the oil film strength, not pump pressure which prevents metal-to-metal contact.

    Abnormally low oil pressure can tell you that there's wear and increased clearances, but it does not indicate inadequate lubrication.

    Yes, you can increase gauge pressure with thicker oil, but that does not equate to better lubrication.

  17. #17
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    is STP compatible with synthetic oil ?? and yes, old acidic oil will chew away at the bearings. At least to Babbit-type bearings. You will see the deformation appearing very differently than worn bearings....looks like someone took a small chisel to them...

  18. #18
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    I've also seen bearings that looked like metal eating mice had been at them. It was a -39 Studebaker (and I didn't buy it).

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    "As long as oil is present, it is the oil film strength, not pump pressure which prevents metal-to-metal contact".............care to comment on hi output oil pumps ??

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    Quote Originally Posted by jackb View Post
    "As long as oil is present, it is the oil film strength, not pump pressure which prevents metal-to-metal contact".............care to comment on hi output oil pumps ??
    So long as a pump has enough pressure to deliver a continuous supply of oil to all contact surfaces, I believe the pressure with which it does so is immaterial. For example, splash lubricated 4-stroke, and most 2-stroke engines run with zero oil pressure, and can last a long time, as long as there is enough oil to splash around.

    Think about it. Wrist pins, pistons, rings, cylinder bores and valve stems never see pressurized oil, but wear out along with the rest of the engine. Who ever tore an engine down because the wrist pins were worn out?

    The highest metal-to-metal pressures are probably cam ramps, maybe rocker arm tips. They get their oil at zero psi.
    Last edited by jnormanh; 05-21-2019 at 08:14 AM.

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