What is normal oil pressure?

NicF · Post by **NicF** » Tue Jul 23, 2013 9:27 am

Recently I've been driving my 5 to work while my kids are visiting and my partner needs a car with four seats. I'm starting to obsess over the oil pressure, do i have anything to worry about here?

100 kph open road cruse, just over 2 kg/cm2
50 kph round town, 2 kg/cm2
Hot idle, 1 kg/cm2, comes up to 2 as soon as I take off.

Hoping to turbo this summer but only low boost and I'd prefer not to have to do a full rebuild at the same time.

warrior · Post by **warrior** » Tue Jul 23, 2013 10:12 am

Sounds low to me...how fresh is the oil and what do you use?

NicF · Post by **NicF** » Tue Jul 23, 2013 10:35 am

It's due for another change, usually Castrol Magnatec which is 10W-40 I think.

chris · Post by **chris** » Tue Jul 23, 2013 11:18 am

It's a 20 year old (roughly) gauge.

How reliable can it be? Does the car sound alright?

Do an oil change and you'll be sweet..

NicF · Post by **NicF** » Tue Jul 23, 2013 11:26 am

Car actually sounds pretty good, has a slightly noisy bearing in either aircon or PS but certainly no knocking. I'll stop worrying about it.

chris · Post by **chris** » Tue Jul 23, 2013 11:55 am

As I said, just keep up on maintenance (I wish I did.. Oops!) and you should be sweet

marcellarius · Post by **marcellarius** » Tue Jul 23, 2013 12:09 pm

The gauges used in the early NAs aren't particularly accurate, some speculate that is why Mazda went to an idiot-light-in-gauge-form in the mid 90s.

If you're worried, get it tested with an accurate mechanical gauge.

My 1994 1.8 had an oil pump failure (ugh.) and as a result the bearings are serviceable but worn; my gauge sits at ~1.5 at hot idle, sometimes as low as 1. Gets up to 3 -- 4 hot when revving the engine.

I stick to the manufacturer recommended oil weights: 10w-30, 5w-30 in cold climates. I change my oil pretty frequently, seeing as the car gets driven hard. I don't have major problems with hydraulic lifter noise (tapping), occasionally on cold starts and after particularly hard driving.

authentic · Post by **authentic** » Tue Jul 23, 2013 6:00 pm

Is it a good or a bad thing that the gauge pins itself at max when it revs above 1000rpm?

WideOpenThrottle · Post by **WideOpenThrottle** » Tue Jul 23, 2013 8:06 pm

From the workshop manual

marcellarius · Post by **marcellarius** » Wed Jul 24, 2013 10:12 am

Authentic: could be thick oil, a bad sender unit or that the pressure release plunger in the oil pump is jamming closed -- normally this valve opens and regulates the oil pressure as engine speed increases. My old pump jammed open occasionally, leading to starvation and the pump losing prime.

authentic · Post by **authentic** » Wed Jul 24, 2013 5:46 pm

I've used 5W-30 fully synthetic since I've owned it. The gauge drops down to ~4kg/cm^2 at idle but pins itself around 2000rpm. The engine barely burns oil, even with my spirited driving (top up maybe once every 700km).

I might have a look at replacing the sender unit anyway. Its probably a bit tired after potentially 22 years of use. I hope its not an oil pump issue cos the pump replacement job looks like a bastard.

SLYDIT · Post by **SLYDIT** » Thu Jul 25, 2013 8:30 pm

cruising around im at about 3.5. at anything above idle...def something not right with your setup

authentic · Post by **authentic** » Thu Jul 25, 2013 8:58 pm

I did remove the needle at one point but I'm like 90% sure I put it back in the right spot. Maybe I didn't.

Snapfrozen · Post by **Snapfrozen** » Thu Jul 25, 2013 9:19 pm

Not sure if anyone has mentioned it. Is your oil level full?

SLYDIT · Post by **SLYDIT** » Fri Jul 26, 2013 4:34 pm

authentic wrote:I did remove the needle at one point but I'm like 90% sure I put it back in the right spot. Maybe I didn't.

that could be your problem. There's a procedure to remove and replace the needles.

SLYDIT · Post by **SLYDIT** » Fri Jul 26, 2013 5:14 pm

heres the procedure from revlimiter...might not help you if you dont have the starting data reference.
http://revlimiter.net/mods/gauge_install.php#needles

authentic · Post by **authentic** » Sun Jul 28, 2013 4:48 pm

Ah so thats how you'd do the oil gauge. I figured out how to do the rest at the time. Cheers for the link..when I can be arsed taking the face off I'll set it correctly haha.

MrGrey · Post by **MrGrey** » Fri Jan 24, 2014 8:21 am

I figured I would resurrect this thread rather than starting a new one but I noticed yesterday my oil pressure has dropped. It used to be around 4 when cold, and around 2 when warmed up idling and around 3 when driving, whilst yesterday It was sitting around 1 when warmed up idling and around 2.2-2.5 when driving.

The oil is full (although it is due for an oil change) and there are no visible leaks anywhere. The only change I have done is adding the ARC intake which should have no bearing whatsoever on things (I would assume).

I will try and do an oil change this weekend, but was wondering if anyone had any ideas on what to look at or what may be the issue?

Thanks in advance

NicF · Post by **NicF** » Fri Jan 24, 2014 8:37 am

Interesting thing is that after I started the thread I did an oil change to Magnatec and the pressure went right back to normal, even though the level was good previously. So see how it is after you change oil.

MrGrey · Post by **MrGrey** » Fri Jan 24, 2014 10:18 am

thanks for the tip, I will do an oil change and update this thread with my results

MrGrey · Post by **MrGrey** » Sat Jan 25, 2014 3:26 pm

you were bang on the money nicF, it was simply my engine telling me that it wanted new oil

NicF · Post by **NicF** » Sat Jan 25, 2014 4:00 pm

Excellent!

WideOpenThrottle · Post by **WideOpenThrottle** » Mon Jan 27, 2014 7:24 pm

Previously I ran 15-40 Fuchs and my gauge was between 3&4 on the factory gauge.

After Hamptons due to a bit of oil loss I bought some Valvoline 20-50 race oil from a crew who were obviously serious about race cars just to get me home.

I have since done an oil change and used this Valvoline 20-50 race oil.On a 50k drive today I noticed the oil gauge now sits between 2&3!

I would have thought the heavier oil would mean higher pressure on the gauge...not lower???

The result doesn't bother me but am a bit curious...is the heavier weight race oil thinner than the 15-40??

Weird or what?

MrGrey · Post by **MrGrey** » Wed Jan 29, 2014 7:08 pm

this afternoon I noticed the reappearance of the low pressure even after I did an oil change. In the morning when its cool I have noticed its fine but it rears its ugly head in the late afternoon (3pm-5pm) this seems to be a symptom possibly caused by the brutal afternoon heat we are experiencing lately.

I will keep an eye on things but it may just be environmental as if it was a mechanical fault then I would assume it would be an issue in the mornings as well.

marcellarius · Post by **marcellarius** » Wed Jan 29, 2014 11:53 pm

WideOpenThrottle: where did the oil escape from? Do you have an actual loss of pressure, perhaps from a leak somewhere or worn bearings?

What is normal oil pressure?

What is normal oil pressure?

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