98 Oil Pressure
01-01-2020, 10:13 PM
#1
98 Oil Pressure I'm looking at a 98 T/A and noticed the idle oil pressure hovers around 20 at idle and goes up to around 40 as the revs climb. My LS1 cars have all idled at 40 and climb to 60-80. I know the temp gauge is different (actual) on the 98s, but would there be a difference in the way the oil pressure gauge reads? Perhaps it may be the earlier oil pump; the oil itself appeared normal. I'm not sure if this should be a concern or not. The car has 81k on it.
01-02-2020, 03:53 AM
#2
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Paul,
A couple things to consider here but, I do have some questions. Is this car an A4 or M6? The difference in stock idle speed settings between these two will typically cause the A4 to show lower readings at idle (especially in gear). But above 800rpm, they should obviously be the same.
All of the 1998-2000 LS1s received the older pump, and these do typically show lower readings across the board than the 2001+ cars with the LS6 pump. My '02 car was just like you said above; 38-40psi at idle (even in gear with stock idle speed, A4 trans) and 60-80psi at higher rpms. But my '98-'00 cars all showed readings that were 10-15psi lower at the same rpm, even when they were new (all A4 cars).
The '98 oil pressure gauge shouldn't read any different based on the model year (unlike the temp gauge). For reference, my low mile '98 (18k) will often read as low as 20-25psi at hot idle (in gear, 550rpm) in warm ambient conditions after plenty of engine run time. In cooler weather, it rarely drops below ~30psi no matter how long the engine is run. In either situation though, it quickly climbs to 40 and above during normal acceleration. On a cold start, it's usually right around 45-50psi.
A couple other things to consider: assuming the current engine oil is unknown, the somewhat lower readings could be due to viscosity differences (all of my listed readings above have been with M1 0w40). Also, the OPSU could be beyond its accurate service life and starting to read a little low.
Ultimately, I wouldn't be too worried about the 20psi reading at idle as oil pressure at higher rpms is really more important than idle readings. With that said, you mentioned above that it "goes up to around 40 as the revs climb" - but does it max out at 40psi or does it keep climbing as you hit higher rpms?
A couple things to consider here but, I do have some questions. Is this car an A4 or M6? The difference in stock idle speed settings between these two will typically cause the A4 to show lower readings at idle (especially in gear). But above 800rpm, they should obviously be the same.
All of the 1998-2000 LS1s received the older pump, and these do typically show lower readings across the board than the 2001+ cars with the LS6 pump. My '02 car was just like you said above; 38-40psi at idle (even in gear with stock idle speed, A4 trans) and 60-80psi at higher rpms. But my '98-'00 cars all showed readings that were 10-15psi lower at the same rpm, even when they were new (all A4 cars).
The '98 oil pressure gauge shouldn't read any different based on the model year (unlike the temp gauge). For reference, my low mile '98 (18k) will often read as low as 20-25psi at hot idle (in gear, 550rpm) in warm ambient conditions after plenty of engine run time. In cooler weather, it rarely drops below ~30psi no matter how long the engine is run. In either situation though, it quickly climbs to 40 and above during normal acceleration. On a cold start, it's usually right around 45-50psi.
A couple other things to consider: assuming the current engine oil is unknown, the somewhat lower readings could be due to viscosity differences (all of my listed readings above have been with M1 0w40). Also, the OPSU could be beyond its accurate service life and starting to read a little low.
Ultimately, I wouldn't be too worried about the 20psi reading at idle as oil pressure at higher rpms is really more important than idle readings. With that said, you mentioned above that it "goes up to around 40 as the revs climb" - but does it max out at 40psi or does it keep climbing as you hit higher rpms?
01-04-2020, 12:36 PM
#4
Thanks, Ryan. The car is an A4 and I didn't notice the oil pressure until after the test drive. So I didn't see how high it climbed the couple of times I stomped it. I only observed it climb while revving it in Park when it was warm. But it even would dip below 20 a bit when adjusting back to idle after revving.
On a point of information, I believe the late 2000's got the upgraded oil pump when other running changes were made, like switching to the 241 heads. There was some discussion of this in a thread years ago. Mine was built in June of 2000. In any case, its oil pressure has read the same or higher than my other two LS1 cars, an 01 and 02, and they were manuals.
On a point of information, I believe the late 2000's got the upgraded oil pump when other running changes were made, like switching to the 241 heads. There was some discussion of this in a thread years ago. Mine was built in June of 2000. In any case, its oil pressure has read the same or higher than my other two LS1 cars, an 01 and 02, and they were manuals.
01-04-2020, 02:22 PM
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Thanks, Ryan. The car is an A4 and I didn't notice the oil pressure until after the test drive. So I didn't see how high it climbed the couple of times I stomped it. I only observed it climb while revving it in Park when it was warm. But it even would dip below 20 a bit when adjusting back to idle after revving.
On a point of information, I believe the late 2000's got the upgraded oil pump when other running changes were made, like switching to the 241 heads. There was some discussion of this in a thread years ago. Mine was built in June of 2000. In any case, its oil pressure has read the same or higher than my other two LS1 cars, an 01 and 02, and they were manuals.
I've always known about the 241 upgrade on the very late '00 cars, but I hadn't heard that those cars also received the LS6 pump. My '00 WS6 was built in May of '00 and still came with the 853s - and this car also had the same sort of (lower) oil pressure as my '98 and '99 cars, vs. the higher readings of my '02 car. So yeah, it sounds like your '00 car could have definitely come with the revised newer pump. 