Stock motor, 250k+ miles, 50psi when driving, but drops to 25psi when idling or in neutral....bad? Good? Ok?
What's an average oil presure at idle?
- Thread starter 85_SS_302_Coupe
- Start date
Stang8URMPRT
Active Member
25 PSI hot at idle is fine. My motor is pretty new and still puts out 65-70 PSI at idle, about 50 PSI at idle after I beat on it for a while, aka top speed runs on the interstate.
Nick
Nick
Mavrick
Founding Member
Isn't the rule of thumb 10psi for every 1000rpm is minimum? I think thats it... if so, your making plenty of pressure!
_jb_
New Member
Michael Yount
Mustang Master
For 250K, 25 psi at idle seem quite reasonable. Keep your eye on it - it'll be a good indicator as to when the bearing clearances/mileage is to the point when you're gonna have to do something about it.
The Shape
Founding Member
That is about what I am getting on mine as well. I actually just switched to Mobile-1 15W-50 from regular 10W-30 and picked up a little more pressure at idle. I mainly made the switch because it is so hot here in the summer though. Your pressure sounds ok to me. That is about what I have had on mine since I bought the car about 2 1/2 years ago and it runs fine.
Michael Yount
Mustang Master
I wouldn't say it's like new - but it's pretty good for 250K. Mine has 62K, with a new pump put in at 52K when I added the h/c/i/exh mods. Mine's 65 psi cold; 38-45 psi hot idle; 55-60 psi max when hot. That's with 5W-30 oil in it.
and what The Shape and Michael are touching upon is something to remember. your motor likely does not have the tight clearances it once had, hence the diminished pressure. with that in mind, you could likely switch to a higher viscosity oil (as The Shape did) to provide more 'cushion' for those greater clearances, help with viscosity thinning, and so on.
i have been curious: does anyone know (using an aftermarket gauge) what stock 5.0's had pressure-wise when leaving the factory? just wondering.
i have been curious: does anyone know (using an aftermarket gauge) what stock 5.0's had pressure-wise when leaving the factory? just wondering.
91LX302
Founding Member
It may be just me but every mustang I've been in that had a stock oil pressure gauge never showed any pressure change, no matter what RPM. Just must be the crappy oem gauges.
Michael Yount
Mustang Master
91LX302 said:
Exactly. My stock Oil pressure gauge has never moved an inch. It stays pointed at halfway all the time.
Meanwhile my autometer gauge goes from 25psi at idle to 55psi at WOT
Michael Yount
Mustang Master
Most American factory gauges (coolant temp and oil pressure) are produced with senders that are designed to dampen any short term fluctuations in pressure - seems their survey data tells them that the average driver is distracted by a gauge needle that moves around with changing revs/temps. So as long as you're in a safe (pretty big range) area - it just keeps the needle still. Bottom line is if you really want to know what your oil pressure and coolant temp. are actually doing, the factory gauges are useless.
That's a very interesting thought there about the gauges....My factory gauge is actually unhooked and there's a cheapo Wal-Mart special gauge on the bottom of my dash. As for the gauges not showing slight changes, that would explain why most stock tachs are off as well? I'm sure they dont do that with speedometers...lol
Michael Yount
Mustang Master
85SS - the factory tachs are off just because they're not very accurate. They almost always seem to read high (show 7000 when the engine's revving 5500 for example), so perhaps Ford did it on purpose so folks would keep the revs down - I'm just making that up, no basis in fact. Gauges like tachometers, clocks and speedometers are supposed to read real time. Over the years, people came to expect those to move around. For some reason, coolant gauges varying up and down by +/- 30 degrees in different weather, or oil pressure varying up and down by +/- 30 psi depending on temps and revs is a distraction for the average consumer. So manufacturers build in hysteresis (a 'lag' effect) so that unless the change in temp or pressure is maintained for a significant period of time, or unless it's of a big enough magnitude, the gauge won't show any change. You can almost think of the factory temp and pressure gauges as showing you temp and pressure history rather than what's going on real time.
Try running a Ford racing oil filter(if not allready).Ifound a 10 psi increase at idle when warmed up compaired to a FL1A filter.
www.pro5o.stangnet.com
www.pro5o.stangnet.com
91LX302
Founding Member
Michael Yount said:
That makes sense. Then again my buddies '93 Chevy P/U has a pretty accurate oil pressure gauge, lots of movement, also has the patented crappy Chevy fuel gauge that moves as much as the oil pressure gauge.
Similar threads
