ok, so during the limited time I got to drive my 914 (72 1.8L) last summer I got concerned regarding how hot my motor was running (pushed 240-250F a couple of times on very hot days: 90-100F). So my intention this winter was to make sure that I had done everything possible to make the car run cooler.

My goal is to positively conclude whether I need an external oil cooler or not.

here is what I have done so far:

1. verify proper calibration of oil temp guage
2. installed all necessary engine tin seals
3. installed late model air deflectors on the bottom on the car
4. plugged all unused heat exchanger openings (pax side only)
5. verified fan is not missing any blades
6. internal flaps thermostat is missing but flaps are in the full open position.
7. rain tray is still installed

So far, operating temps haven't exceed 220F(once), but air temps have only been in the 80's so far.

My question now is, should I start using synthetic oil? Will Synth oil make the car run cooler or just withstand heat better (i.e. not thin out)?

recommendations are welcome and thanks!!

yes, synthetic will help you, and not *just* because it'll keep lubricating at higher temperatures, although if that alone saves your motor i wouldn't call it a bad thing ...

what i didn't see in your litany of services performed is making SURE that you don't have a nice insulating blanket of leaves, feathers, and rodent nests on the top of the heads, cylinders, and especially the top of the oil cooler. oh - those are also dandy places for shop towels, plastic bags, and Kleenexes to get sucked to and deposited.

make sure you're geting air through all the places it's supposed to go through ...

My buddy Stef has been doing a lot of engine rebuilds at his shop lately, and has shown me something that has changed my mind about synthetics 2 or 3 times in the last few weeks. When he tears down engines that were switched from regular oil to synthetic, there is a really scary build up of what looks like black waxy tar on the cam/valve train and bearing areas. He just did a Lexus, and the build up looked to be the cause of an oil starvation cam flattening.

Keep in mind, he was not telling me he was positive of the cause and effect relationship between the waxy crap and the synthetic switch, but he said every time he has seen this stuff, the car owner tells him they switched from regular to synthetic oil at some point. Based on that, I don't think I'll be using synthetics in the future.

QUOTE (aircooledboy @ Feb 21 2005, 03:31 PM)

When he tears down engines that were switched from regular oil to synthetic, there is a really scary build up of what looks like black waxy tar on the cam/valve train and bearing areas.

i'll be tearing down the 2,2 in the 911 in the very near future, and i'll let you know what, if anything, unusual i find.

it was running God Knows What before i got it (Castrol of some description at least for a while) but it's been on Mobil-1 for the last 2 years.

oil temps of 240 to 250 are damn hot, should be 20 to 30 degrees lower than that ( street driving ) . do you have the little air spoilers under the car ( front edge of engine bay ) and i would take a look at your oil cooler it might be partially blocked.

and there is some schools of thought that syn oil doesnt cool as well, but reg oil breakes down at like 250 degrees so even going to syn oil for the high temp reasons was enough for me.

i read an article a few years ago that said dyno oil looses as much as 50 % of its lube qualitys at 250 or so degrees.

I switched over from dino to synthetic in my chrysler v6 daily driver, and from what I can see of the valve train through the oil fill, it still looks nice and clean. No sludge. Then again, I've always changed my oil frequently, which I am sure helps.

You probably should check your timing and mixture.
Make sure you aren't too lean and that your timing is right.
Either of these being off can cause overheating.
I'd be more concerned with these than running synthetic oil.

--- bill

You gotta ask yourself the question. If those people recently switched to synthetic and then just had an engine failure bad enough to warrant a tear down, they probably switched to synthetic in hopes to cure whatever problems they let creep up by not changing oil frequently enough and it was too late anyhow. Know what I mean?

QUOTE (ArtechnikA @ Feb 21 2005, 12:23 PM)

what i didn't see in your litany of services performed is making SURE that you don't have a mice insulating blanket of leaves, feathers, and rodent nests on the top of the heads, cylinders, and especially the top of the oil cooler.

I agree 100% with this statement. You would be surprised how fast crap builds up on the cylinders. Make sure the fins are free of debris

I stopped using oil, some guy here told me water cooled cars run better, so I have been using water for about a month.

I hope I don't have to take anymore of this medicine... it makes me... uhh... punchy..

M

I only have 15K miles on a rebuild, so I am "fairly" certain the cylinders are free of debris....but I will check anyway.

Timing and mixture were recently adjusted.

I am thinking I will run synthetic at my next oil change (and before it gets really hot) if not for anything else than just protection.

If it starts pushing 240/250F again, then I know what to do.

thanks everyone for the .02

I once blew up a riding lawnmower that was on synthetic (long story). It smelled real bad every time I went full throttle under load, then the con rod left the block. . . Drip a drop on hot headers and learn that smell - If you smell it again, Shut Down! That is how Mobil 1 will save your engine.