Chasing down oil leaks...
Join Date: Nov 2001
Location: nearly Kingaroy, Qld.
Low oil pressure - thicker oil?
I've put a S pac cluster in my car ages ago and only finally got around to putting in a oil sender for the gauge last week.
Went to the wreckers and got a sender with the intention of doing it at the same time as an oil change. Now I generally run Shell Helix 15W/50 (blue), but this time I got the lower spec 20W/50 Helix (yellow), mainly because it comes in a 6L bottle instead of 5L.
Anyway installed the sender and it didn't work. Was heading out west to work for a week so I stopped in at the wreckers on the way to get another one, let it cool down for 5 mins and then changed it still quite warm. At least the CFI manifold makes it a reasonably burn free job LOL..
The second one worked. Anyway for the question...
With the 20W/50 oil, at cold the pressure reads 3/7 (gauge reads from 0 to 7) which I think is good. As the oil heats up the pressure drops down to 2/7 when above 1500rpm, and below 1500rpm to idle, sits just under 1/7, which for my liking is too low. Also a slight rattle is noticable at the low pressure/low reading (which makes me believe the gauge is reasonably accurate), but its not low enough for the light to come on.
Now if I ran a thicker oil such as 20W/60 or something, I am assuming that the hot oil pressure will be higher. Maybe my oil pump is getting long in the tooth. How thick oil can a oil pump handle before you get problems? I see that Shell makes a 25W/70 oil that they call Sport or something.
Any suggestions? Filter is a purolator btw and oil was flushed with Nulon flush before change. Oil is brand new. Engine is 3.9L CFI.
1988 EA Falcon Pearl Green
Head gasket replacement count - 1