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Old 11-10-2008, 12:33 AM   #1
fishheadback
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Member#: 68120
Join Date: Aug 2004
Chapter/Region: MWSOC
Location: KANSAS!!!
Vehicle:
1998 RS 2.0 vf23 STi
& MK6 GTI

Default Another oil pressure question. . . .

Sooo I somewhat recently rebuilt my 20k STi motor in the beginning of April. I assembled it on the loose side of specs with ACL Race bearings. It has about 1300 miles on it now, I dont drive it much.

Ive been running ROT 15w40 in it since I rebuilt it and I havent had any issues with it at all.

Just today I changed the oil and decided to go with ROT 5w40 syn and noticed my oil pressure seems a little low to me. With the 15w40 I was around 12-15psi at hot idle, around 60ish highway cruising. Now with the 5w40 Im around 10psi hot idle and 45-55 highway cruising, 3200rpm. Up to around 5-6k Im a tad over 60psi with the 5w40. I havent taken it over 6k because I was a little concerned. These readings are from the top oil galley in the front with a prosport premium gauge.

Should I be concerned with this?? Ive also thought about getting a sandwich plate to get my oil pressure readings from, but Im not sure if it would make that much difference.

Input anyone??
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Old 11-10-2008, 09:56 AM   #2
bobjr94
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Location: Roy,WA
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15 WRX, 04 wrb STi
85 wrb BRAT

Default

The 5-40 will be thinner and easier to move, so the results you have seen are normal and you should have gained some mpg from it also. If you still are getting 10lbs per 1000 rpm or more ( 10lbs@1000rpm,40lbs@4000,etc ) you should be fine, as that is usually a good rule of thumb for oil pressure. I used 5-30 in my wrx and it had 100,000 miles on it when I sold it and not not 1 motor problem.
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Old 11-10-2008, 02:45 PM   #3
fishheadback
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Join Date: Aug 2004
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Location: KANSAS!!!
Vehicle:
1998 RS 2.0 vf23 STi
& MK6 GTI

Default

Ok, thats somewhat what I gained from browsing other threads but I wasnt 100% sure. My cruising pressure seemed a little drastic as far as pressure drop. I will keep an eye on it for sure. Im still not totaly convinced that this oil is heavy enough for 8k rpms though. Other people run it and like it so who knows.

Any input on getting an oil filter sandwich for pressure readings instead of the top galley??
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Old 11-14-2008, 08:38 PM   #4
yamarocket630
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10 psi per 1k rpm is considered optimal for most engines. Any more is just unnecessary drag.
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Old 11-14-2008, 11:07 PM   #5
fishheadback
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1998 RS 2.0 vf23 STi
& MK6 GTI

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Hmm, well I took it out the other night and gave her a little hell. I reset the max on my gauge and ran her all the way to 8k. Seems my pressure doesnt go over 65. That wouldnt quite fall into the 10psi per 1k rpm. It seems fairly smooth with no wierd stuff. Guess ill let it fly for a little while.
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Old 11-16-2008, 06:09 PM   #6
fishheadback
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Member#: 68120
Join Date: Aug 2004
Chapter/Region: MWSOC
Location: KANSAS!!!
Vehicle:
1998 RS 2.0 vf23 STi
& MK6 GTI

Question To shim or not to shim. . . . .

Well now im having water pump issues so Im going to dig into that. Which means timing belt and associated parts will be coming off.

Question- Should I shim my oil pump while Im in there??? Just to be on the safe side.
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