Oil Pressures in Freezing Weather

[scam75]

Hi Guys

Obviously covered this topic to death in my engine build thread, and as it turns out I have really good operating pressures as you would hope on a fresh engine.

And yes, I am paranoid about this now! So, as you know, it's been sub-zero of late. I have noticed on a frozen (literally) cold start up, my oil pressure light stays on for 3 or 4 seconds as the pressure builds, and it probably takes about 10 seconds to hit 4.5 bar, this is without revving it at all. A couple of taps on the throttle at this point and it quickly sees 5 bar idle, then everything is perfect after that once initial pressure is built up. Starting it when it's heated up, it only takes about 2 seconds to hit 5 bar.

I am using 10w/50 fully synth Total Quartz Racing oil. The oil is at max on the dipstick. I am using the correct Mann oil filter with 2 non-return valves in it. Is this oil maybe slightly too thick now for a fresh engine, is it the freezing temps, or a combination of both? Or is it quite normal in sub-zero temps? Or am I chasing an issue?

Thanks in advance as ever

Stuart

 

[blade7]

Car garaged or outside? Isn't Porsche spec something like 5w40, perhaps that was for start up at the below freezing temps we've been having this winter. My car has always been garaged, but it did drip on 5w40 when hot.

 

[scam75]

Yeah Porsche spec is thinner than what I am using. Car is outside in a frozen tundra! The fact it's fine when heated up, makes me think it's just a combination of oil on the thick side and freezing temps. There is also the fact the pressure sender is quite high up on the block maybe causes a slight delay in the readings from cold start, exaggerated when things are freezing. Dunno, just guessing with that theory. The pressure would certainly build quicker with thinner oil.

I suppose what I'm really asking, is 3 or 4 seconds of the oil pressure light on, at idle on a freezing cold start, anything to worry about?

 

[geedee]

Only guessing here, but as the oil pressure switch is likely to be a mechanical device it`s operation could well be sluggish in sub zero temps..?
Similarly at the other end the oil pressure system the relief valve might also be temp affectedwhen really cold.

 

[scam75]

Yes both possible I suppose. Should add that the engine is quiet while the pressure is building on the gauge. So I think that lessens any concerns. No lifter noise or anything untoward.

To be 10 degrees warmer tomorrow. Will see how it is.

Cheers

Stuart

 

[scam75]

It's about 12 degrees today. From cold still took about 3 seconds for oil light to go out and about 10 seconds to reach 4.5 bar (no revving). With hot start the light goes out almost instantaneously and takes about 2 seconds to reach 4.5 bar. No bad noises whatsoever during those 10 seconds.

Pressures are great when driving. At full heat soaked idle, it's over 3 bar, and rises above 4 bar by about 1.2k revs.

I think I should not be too worried about the cold starts, but will continue to monitor it. But would be interested to hear how other peoples cars are from stone cold.

Cheers

Stuart