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Old 15th April 2024, 09:24   #1
ashy90
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Default KV6 oil pressure

What is the minimum acceptable oil pressure on a 2.5 v6 when hot?

I’ve seen figures of: min 3 bar @ 3k rpm, and min 1 bar at idle, but unsure if these figures are when hot or cold…..I am assuming hot?

In practice, are these figures what can be expected on our engines now they are old?

Last edited by ashy90; 15th April 2024 at 10:38..
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Old 15th April 2024, 10:04   #2
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Iíve seen figures of min of 3 bar @ 3k rpm, and min 1 bar at idle, but unsure if these figures are when hot or coldÖ..I am assuming hot?
Those are the figures from RAVE Ash and I too would expect them to apply to an engine at normal operating temperature.

What's your reason for asking? Do you have an oil pressure problem?

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Old 15th April 2024, 10:39   #3
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Yes, I done a test yesterday when up to full temp, and was getting 3.5 bar @ 3k rpm (so good) but only 0.8 bar at idle (not so good? Or to be expected on a 120k mile engine?)
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Old 15th April 2024, 11:20   #4
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Are you using 10W40 oil Ash? When was it last changed?

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Old 15th April 2024, 16:10   #5
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Drained the oil out immediately after doing the oil pressure test yesterday and replaced the filter, re-filled with 5w40 on this occasion.

What would you expect the oil pressure to be?
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Old 15th April 2024, 16:37   #6
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re-filled with 5w40 on this occasion.
In theory it shouldn't make any difference at running temperature but MG Rover recommends 10W40 for your engine. You could try that the next time you do an oil change.

How are you measuring oil pressure?

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Old 15th April 2024, 18:52   #7
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Yes I canít see the 5w40 causing low oil pressure either.

Oil pressure measured with an oil pressure gauge where the oil pressure switch screws in.
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Old 15th April 2024, 19:03   #8
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Oil pressure measured with an oil pressure gauge where the oil pressure switch screws in.
Wow, you mean business don't you!
So to return to your earlier question ...
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... only 0.8 bar at idle (not so good? Or to be expected on a 120k mile engine?)
I honestly don't know. I doubt that many people have measured their oil pressure as you have done.

I'd say if it's not illuminating the oil pressure warning lamp and there is no discernible effect on the engine, don't worry about it.

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Old 15th April 2024, 20:10   #9
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Yeah the oil pressure light came on when I last used the car - had just come off a 60/70mph dual carriage way and come to a stop at a set of lights and it came on, then went off when I pulled away and would come back on at low rpm/idle.

Iíll see how it goes having changed the old oil and cleaned the oil pressure switch. May repeat the oil pressure test on my ZS 180 to confirm the gauge is accurate
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Old 15th April 2024, 21:09   #10
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I used to have a Mitsubishi 3000GT for which the manual stated 10W40 oil should be used, however a lot owners used to swear by this 10W50 oil which has a slightly higher viscosity at temperature

https://www.ebay.co.uk/itm/174774140...mis&media=COPY

It might be just enough to boost your oil pressure for a while. It is a bit pricey though! I should state that I have never personally used it in a KV6, so can't confirm any effects, positive or negative.
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