911caught in stopped traffic, oil light- flashing on 0.5bar

[Jaz]

Hi Guys,

I have a 1983 3.0 SC. on two separate incidences I've been caught up in very slow moving/ stationery traffic (UK, external temps hovering around 20 degress celcius) for c.40 mins.

specifcially the oil pressure with increase temperature build-up appears to causing a dropping pressure (not level) from just-over 1 bar pressure towards 0.5 bar (making the oil less viscous) upon which red oil pressure light warning light comes on. Upon driving forwards (slowly) the problem has gone . Not good I guess.

The car has been recently been fully serviced, has semi-synthetic Fuchs oil and features only a one year old OEM fender/arch oil cooler.

Any suggestions as to how I can fix this, or work towards one.

ie
1- put in a front bumper plastic air intake.... though in stationary traffic may do no good.
2- or cut a bit from the under side of the bumper.... though in stationary traffic may do no good.
3- use thicker oil...mhh dangerous.

Regards,
Jaz

[tabasco]

What is Fuchs oil ? What grade ?
Air cooled engines require pretty thick oil.

[Turboo934]

Do you have a fan on your cooler. I run Aero Shell 50wt. hot weather 40wt cooler weather.

[IROC]

According to the original owner's manual for my car (with the 2.7L CIS engine), this was acceptable. It specifically mentioned the fact that the oil light may come on at idle.

Are you running 20W50 oil? I probably would.

[VFR750]

My car does this too. Especially between Autocross runs. Even when running 15W-50 oil.

I raise the idle speed a little to ~1100 rpm, to build a little more pressure and to increase the fan cooling flow. Oil light goes out.... Been doing this for as long as I owned it. 23,000 miles later, no issues.

[wildcat077]

Originally Posted by Turboo934

Do you have a fan on your cooler. I run Aero Shell 50wt. hot weather 40wt cooler weather.

Funny you should mention Aeroshell 50 Weight,i used to run that in my road race superbikes in the eighties... lol
Forgot all about it... I`m going to check the specs on that.Right now i`m using Mobil 1 15w50 but i`m always open to changes !!!

[Jaz]

Fuchs is a german oil producer,selling through a German car part reseller in the UK .

Specifically i'm using 10/40 grade semi synthetic grade.Is this too light for a 3.0 SC?
My car does not have a fan .

I've been advised to run the car to hot and then check the two pipes going into the front cooler are hot, which will nsure circulation is there, if not then to not trace back them to the rear tank up to the the pump regulator to check the heat consistency along the length and no kinks. May even point to a fault regulator. will check at end of my drive back home.

[tabasco]

I'd think 10-40 is too thin for those engines, especially if you have heavy traffic.
15-50 would be better.

[justinp71]

I believe semi-synthetics are also thinner two... I know they are common to make cars leak.

[kidrock]

I would immediately do 2 things;

1) ensure the base idle speed is correct. If the idle is too low, this will cause the problem you are describing.

2) I would do a search on this site for the "Ultimate Oil Thread", and research the best oil to use. I recommend a quality 20w50.

If your problem continues, it may be suggesting that your motor is possibly getting tired. Compression tests and leakdown tests are probably in order, as will be a subsequent rebuild.

[brads911sc]

Originally Posted by kidrock

i would immediately do 2 things;

1) ensure the base idle speed is correct. If the idle is too low, this will cause the problem you are describing.

2) i would do a search on this site for the "ultimate oil thread", and research the best oil to use. I recommend a quality 20w50.

If your problem continues, it may be suggesting that your motor is possibly getting tired. Compression tests and leakdown tests are probably in order, as will be a subsequent rebuild.

+1

[dentist90]

You mention that your oil pressure goes down to .5 Bar when hot and idling, using 10w40 semisynthetic. You did not say what your engine oil temp is reading at this point.
The apropriate grade for these cars depends on the ambient air temperature and driving habits. My owners manual recommends from 5w30 to 20w50, depending on ambient air temp. It also states that it is very common to have this kind of low oil pressure at warm idle and that the warning light may illuminate. It does not indicate a problem if the light goes out if you raise engine speed. If this is a normal driving condition for you it would probably be advisable to go to a higher viscosity, 15w40 or 20w50. The higher viscosity may be just enough to bump the pressure up. Oil pump seems to be working since you still get good pressure when the engine revs.
IF your engine oil temp is very high while you are idling in traffic you have a different problem. If your engine is running excessivley hot it is time to check the oil thermostats, cooling fins for debris and considering an electric fan on the external oil cooler.

[SteveinTO]

When I'm occasionally stuck in traffic and the oil temp is up and pressure down, I try to hold the idle at around 1500-1800 RPM, and/or maintain a constant speed in first gear, rather than lurching with traffic. This put less abuse through the clutch, brings the oil pressure up a bit, encourages stronger oil flow through the fender cooler, and speeds the air flow over the cylinders. That's about the best you can do, other than shutting down and letting it cool off by the side of the road.