coletrickle Posted April 16, 2012 Share Posted April 16, 2012 Hi all, Appreciate there have been numerous threads re oil pressure in the past but none that I've seen really explain this! For the last year and a half oil pressure at idle has been around 15. I did around 650 motorway miles this weekend. Around 600 miles in I noticed oil pressure at idle has now jumped to 30. Pressure still moves 'normally' and settles around the 60 mark at 60 in 6th. Any ideas why this might have changed? I'm hoping that, assuming oil level is normal, it's nothing to worry about.... But it's a bit odd! Quote Link to comment Share on other sites More sharing options...
Ekona Posted April 16, 2012 Share Posted April 16, 2012 I'm assuming you've checked your oil level in the last 18 months? Quote Link to comment Share on other sites More sharing options...
speedwell Posted April 16, 2012 Share Posted April 16, 2012 I think this is theoretically posible... A lot of short trips means the oil never gets hot, so condensation and other contaminents of combustion are not evaporated away, as they might otherwise be...so the oil gets thinned,hence the reduced pressure. A lot of motorway work gets the oil up to temp and puts things right. Well it's a theory... Quote Link to comment Share on other sites More sharing options...
coletrickle Posted April 16, 2012 Author Share Posted April 16, 2012 Thanks for the replies. Probably should have added a little more info: Car was serviced 3 weeks ago. Oil level was correct then, will re check next daylight opportunity. Car usually used for two circa 30 mile motorway journeys a week so should have been well upto temp previously. Quote Link to comment Share on other sites More sharing options...
SteveW Posted April 16, 2012 Share Posted April 16, 2012 What rpm does your car idle at? I typically see 28-30psi at 700ish rpm. 15 is rather low. The only car I've known to be lower than that was one where pressure was being read at the top of the engine and that was 12. Not sure what pressure drop you see on the zed from pump to top of the heads? Quote Link to comment Share on other sites More sharing options...
Ekona Posted April 16, 2012 Share Posted April 16, 2012 As a rule, if the oil level is fine and the pressure gauge needle isn't going to either extremity of the scale in use, then there's no problem. Quote Link to comment Share on other sites More sharing options...
Ebized Posted April 16, 2012 Share Posted April 16, 2012 What oil did the garage use - sounds, from what you have said, that the oil viscosity used during the service is something different to that which was in the car before, aside from the old oil's properties having perhaps lost their full worth. Quote Link to comment Share on other sites More sharing options...
coletrickle Posted April 16, 2012 Author Share Posted April 16, 2012 Used to idle at a shade over 15 when thoroughly warm (which from some brief research on here sounds about right?) For some reason, mid journey, this has changed to 30ish. Seems a bit odd! I've done around 1500 miles since the service so not sure that the change mid journey can be attributed to new oil? Trying not to worry but it's annoying not having a clue why it happened! Quote Link to comment Share on other sites More sharing options...
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