jsrieck

If one is doing a lot of short trips around town, should you be more gentle with the engine, that is, keep the revs below 4500? But I did read somewhere that it is important for these engines to be taken up past 4500 often to keep everything going smoothly? But then I read somewhere else that you shouldn't take the revs over 4500 unless you have been driving long enough to get the engine warm! How long does it take for the engine to get warm?

Confused...thanks!

aeroman

never go above 4000 until the oil is at 9 O clock on the oil gauge.

TEN DOLLAR

In the Winter in the UK, my temp gauge will hardly ever go above the 7 o clock position under normal driving conditions. In fact it only went up to the 9 o clock position once or twice in the summer, in traffic. It was a crap summer though.

Aeroman, what is your airborne steed? Mine's a B777. I've got 3 stateside trips next month. Time to buy up all your cheap 964 parts!!!!!

TD

ilko

Really? My car rarely goes to 9 even at the track...

race911

And I'm likely to be nowhere near 9 when it hits pit out.........especially on a winter day. After all the trashed, abused, and pissed on 911 engines I've pulled apart over the years only to see little, if any, wear, I don't sweat it.

Guards964

Mine doesn't get near 9 o'clock on the guage, even after I've been running it hard for an extended period. Even this last summer, It never got up that far even in stop and go traffic...

Scott
'92 Guards Red C2

TR6

Conventional wisdom says until it reaches 8 o'clock... Not 9. But as many have stated, in the winter, it may not see anything higher than 7 o'clock, at which point I think would be fine to rev it up. What you don't want to do is to rev it above 4K rpms until you at least see it warming up on the gauge. The oil is too thick when it is first started cold to provide ideal lubrication flow for high revs.

elbeee964

ahhh... here's another topic to ponder:

dutchcrunch

if you start from cold and as you drive the car you will see the oil temp gauge start to rise and then dip back down, this lets you know the oil is up to temp and the thermostat is open and oil is flowing thru the oil cooler, then you can romp on her. as for reference usally in the 8 oclock then to 7 oclock position which could vary from car to car

elbeee964

After the thermostat opens, for sure -- but what's at stake before that when the oil temp is plenty warm?

TR6

Lonnie, that's a great question. But I don't think that is an issue (whether the thermostat is open or not) because the concern is the oil temperature (and therefore the viscosity) in the engine. Not in the oil cooler. If you think about it, we don't really care whether the thermostat opens or not (unless our oil gets too hot!). We care about the temperature of the oil (and therefore the lubrication and flow properties) circulating in the engine itself. But what do I know, I'm an arm chair shade tree mechanic! I also would like to hear some expert opinions.

CabrioArtie

Okay, since I am new to the car I will ask what I feel is the obvious question. Since this is my first oil/air cooled car. On my water cooled cars the thermostat is designed to maintain the water at a predefined temperature. Isn't the thermostat in our cars designed to do the same? Shouldn't the car always warm up to 9 o’clock unless the weather is so cold that even with the thermostat completely closed it won't warm up to 9 o’clock?

I would think if the thermostat even starts to open that the car is at running temperature. There is only one reason I could think of as to why it would open earlier, the thermostat is malfunctioning. Please tell me where I am wrong as this doesn't seem to be stated anywhere above and I want to learn the idiosyncrasies of my car.

t-shark

When I rev very aggressive, I sometimes have a very bad smell in the car (a moment). What could this be? It is close to but doesn't smell like burned rubber.

Andy Roe

The thermostat usually opens at around the 8 o'clock mark on the temp gauge. This is usually around the time that the oil thermostat opens to allow oil to flow into the oil cooler at the front of the car.

I generally just wait until the oil gauge has started to rise before venturing higher up the rev range, and not necessarily until it hits the 8 mark.

springer3

I don't think the oil is the real issue. Cold oil is a fine lubricant and coolant, and quality oil flows even when cold.

The real issue is the metal parts of the engine. Thermal expansion causes thermal stress as different parts of the engine heat up at different rates. The exhaust can get red-hot on a short full-power run. Do you want red-hot exhaust when the rest of the engine is still cold? A slow warm up lets the bottom end reach temperature before a high-power run gets the heads and exhaust up to their peak temperatures. Similar to breaking in a new engine, you don't risk high RPM or high power operation on a cold engine to avoid hard running on parts that are not yet broken in. Oil temperature tracks better with the bottom-end temperature, and therefore that is the gage to watch to see if the engine is warm enough for high speed and high power operation.

A big electric power plant can't be run at full power until it has warmed up for a day or so - just to allow everything to get to the proper shape, size, and temperature. A large nuclear power plant takes 3 days to reach full power, simply to avoid cracking the thick pressure vessel walls during warm up. The little power plant in the 964 needs only a 10 to 15 minute warm-up before going to full power.