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Oil Pressure when hot?


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What should my oil pressure gauge be reading when the engine is hot/on a long run? I recently went to Spa and back which is probably the longest run the car has done for some time. By the time I got to the Tunnel the oil gauge was only just off the bottom. When I checked the oil it had used none in 600 miles. Is this normal?

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Nope. Oil pressure ought to be higher than 110,000 mile crankshaft (new bearings, though) is around 50 psi at 3500 rpm when hot, on Castrol Edge 10-60.  If you mean at idle...then the minimum is then 5 psi. Book says 35psi minimum at 3500 and 45 psi at 6500....for a wet sump 82 turbo, but all wet sump 900 series should be similar.

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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  • 2 weeks later...

Hi Matthew,

On an S1, hot, normal to spirited driving, at idle, the needle should be just above the red zone (right on the line, but fully on the green side of it). This is approximately 20psi. In cooler weather or on a fresh engine it may be higher, up to a "red zone's width" of green space.

Same conditions (hot, warm day, etc.), while on the motorway, the needle should be in the middle of the gauge (~3K rpm). This is approximately 55-60psi. It will be noticeably higher in cool weather or rain, as water misting the oil cooler will keep the oil cooler.

With all of this said, if your readings are low, the first thing to do is connect a mechanical gauge to check the oil pressure, as any issue with the dash gauge, sending unit, alternator, ground, etc., can cause a low reading on the dashboard gauge. Turn your lights on and off and see if that affects the oil pressure gauge...

By the way, those minimum numbers in the workshop manual are minimums, not 'normals'; on a healthy engine with tens of thousands of miles, you should only see those minimums when really flogging it on a hot summer day.


Tony K.

Tony K. :)


Esprit S1s #355H & 454H

Esprit S2.2  #324J

1991 Esprit SE

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I recently had to buy a new oil pressure sender unit for my S1. The ones supplied by SJ are bigger than the original so you have to make a new mounting bracket and the original pipe on my car didn't fit the new sender so I had to also buy the pipe to go with it. The needle sits above the red and into the green at tickover and then about half way when I rev it - haven't actually driven mine yet. So yours definitely doesn't sound right.



Lotus Esprit [meaning] a 1:1 scale Airfix kit with a propensity to catch fire

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