Oil Pressure/temp and water temp - what's "normal"?
06-12-2021, 04:15 PM
#1
Instructor
Thread Starter
Oil Pressure/temp and water temp - what's "normal"?
I have a stock (from the engine perspective, anyhow) 1992 968 with aftermarket oil temp/pressure and water temp gauges. We're just getting into "peak summer" where I'm at, and I can definitely notice a difference in "standard operating" temps with the weather.
All temps Fahrenheit.
Ambient air temp is ~95, maybe peaking at 100.
Oil temp ranges from 175-185 (moving at 40+mph), can get into low 200s (208-210 is max I've seen) when idling.
Oil pressure has always been "good" - obviously varies with oil temp and engine speed. However - I just noticed today that at higher temps (200ish), when idling, it can drop down to 18-20psi (my oil pressure light blinks red at <20psi) - is this too low? Never drops below 18, and as soon as you give it any gas, it bumps back up into 25-30+ psi. Dash gauge shows ~1bar at same time - oil pressure light in dash never comes on. I plan to check idle pressure once the car has cooled down - at a cold start, it's obviously MUCH higher - believe I've seen 60-70psi, lowering quickly as oil temp raises. Also just realized that when mechanic did last oil change (after a oil pan gasket replacement), they refilled it with "LMO Motor Oil 5w-40 Leichlauf HT-1L". In the past when I'd done my own changes, I used Liquid Moly 20w50. Could the difference in weight/viscosity also be causing the low idle pressure at higher temps? I assume I should get it back to 20w50?
Water temp used to run 180-190 in more reasonable ambient temps, but I often see it around 220 now. Oddly, while aftermarket water temp gauge normally stays right around 220 when it's hot out, the dash water temp gauge can vary from middle of the two "hash marks" on water temp gauge to a high of just under the upper/middle mark (nowhere near red area). I'm assuming this is an OK range for the 968, especially given high ambient temp?
All temps Fahrenheit.
Ambient air temp is ~95, maybe peaking at 100.
Oil temp ranges from 175-185 (moving at 40+mph), can get into low 200s (208-210 is max I've seen) when idling.
Oil pressure has always been "good" - obviously varies with oil temp and engine speed. However - I just noticed today that at higher temps (200ish), when idling, it can drop down to 18-20psi (my oil pressure light blinks red at <20psi) - is this too low? Never drops below 18, and as soon as you give it any gas, it bumps back up into 25-30+ psi. Dash gauge shows ~1bar at same time - oil pressure light in dash never comes on. I plan to check idle pressure once the car has cooled down - at a cold start, it's obviously MUCH higher - believe I've seen 60-70psi, lowering quickly as oil temp raises. Also just realized that when mechanic did last oil change (after a oil pan gasket replacement), they refilled it with "LMO Motor Oil 5w-40 Leichlauf HT-1L". In the past when I'd done my own changes, I used Liquid Moly 20w50. Could the difference in weight/viscosity also be causing the low idle pressure at higher temps? I assume I should get it back to 20w50?
Water temp used to run 180-190 in more reasonable ambient temps, but I often see it around 220 now. Oddly, while aftermarket water temp gauge normally stays right around 220 when it's hot out, the dash water temp gauge can vary from middle of the two "hash marks" on water temp gauge to a high of just under the upper/middle mark (nowhere near red area). I'm assuming this is an OK range for the 968, especially given high ambient temp?
06-13-2021, 09:50 AM
#2
I believe the wsm (section/page 17 . 9 ) specs 2.5 bar as the minimum hot (180F) idle oil pressure for the vario assembly to function.
edit..with the cooling system AIR tight, the needle stays at or below the first hash on the temperature gauge moving above 35 mph.
edit..with the cooling system AIR tight, the needle stays at or below the first hash on the temperature gauge moving above 35 mph.
Last edited by thomasmryan; 06-13-2021 at 09:55 AM.