The old owner of my car thought synthetic oil was best. From my and Steves readings it is found that synthetic dose not transfer heat well. And that is not good for air cooled moters.

I have heard it is not a good thing to switch.

How do I change form snake Oil to regular?
What weight should I run?

I have a 75, 2.0L, 4 cyl

AM I STUCK WITH SYNTHETIC????

i'd be interested in your results that indicate synthetic oil is not good for aircooled engines, this is based on what data?

I have been using synthetic for years in some of my cars, air and water cooled. My Vanagon has 175K miles on it with synthetic since new, pulled teh valve cover off, and the inside is clean and shinny as new, no sludge build up, I think that is a good thing about synthetics, they really do seem to keep the engine clean.

I also recall that Mobil One makes a synthetic specifically for Vee Twin motor cycles (air cooled), so sythnetic in general must not be too bad for air cooled engines.

I run the thicker weights in my aircooled cars, Mobil one 15w-50, or Valvoline synthetic 20w-50 work well, holds good oil pressure on my used engines. You could probably use a lighter wieght on a new tight motor.

I do not use synthetics in my 61 Bug, cause it ain't got no fancy full flow filter, so i change oil every 1500 miles or so, synthetic is too expensive for that change interval.

You should have no problems running synthetic oil, just pick the right weight, and confirm with an oil pressure reading. An old leaky or oil burning motor should probably get regular oil, for cost reasons.

I see know reason why you cannot change oil types, they all are supposed to be compatible with each other, and after draining a hot motor for a while , most of the oil will be out, if you get freaky about mixing, then change the oil, with a long drain period, then drive the car a bit to heat it up again, re-drain, and re-fill again, that ought to get most all traces of the synthetic oil out of your engine.

good luck

You can change oil any time you like. Change the filter at the same time.

You shouldn't add oil (top-up) of a different brand or weight to what is in the engine... they don't always mix right, but if you are draining and replacing, do what you like.

Synthetic is in just about every way better than mineral oil, and doesn't break down from heat the way mineral oil does (which is why the change interval is normally 3000 miles) - people have run up to 10k with Syn
I thetic, although I've heard it said that you should replace the filter more frequently than that.

Don't put synthetic gear oil in the 901 tranny though - apparently it is too slippy and stops the synchro mechanism from working.

I ran Amsoil Synthetic in my 1.7 and it ran very well, and through some pretty high stress work (DE days etc) with no problems what so ever.

YMMV

My 914 leaks enough oil that synthetic isn't worth it. If I had a 100% fresh non-leaker though I'd use synthetic. If you get oil leaks you could always switch to regular oil. Both are 100% compatible with each other.

you are not stuck with synthetic,

but you ARE better off with it.. Jake's done the tests to prove it... your oil temps are lower with synthetic, and friction is reduced... and it doesn't leak MORE than dino oil...

do what you want, if you want to run on dino, use Kendall or Rotella-T dino-using members here swear by them... change the filter at the same time, and don't mix dino with syn...

Keep using the synthetic. If you have any leaks, just fix them. The oil return tubes on my 911T were leaking as well as the oil lines. Now that they are all fixed, no more leaks :-) I'm running 15w50 M1 syn in it. Still unsure of what drain interval i'm going to run. Probably filter changes every 3-5k with drain at 9-10k miles. That's a reasonable life expectancy. Royal Purple claims longer drain intervals as well as Redline, Amsoil, etc, and I guess you could assume the same with Mobil's new extended drain interval oils :-)

Pete: Still awaiting your and Steve's readings on heat tranfer with synthetic oil. Can you tell us all what data you have on this subject?

thanks

dave

Id agree with all of that, the only with the syn is that if your car is already leaking with conventional, than syn can make the leaks seem worse, because it is smaller on a molecular scale and thus will find the leaks more easily than conventional. If you are not leaking, syn will dissipate heat better, lubricate better, and last longer-which is why it's more$$$

Sorry dave my last reply did not make it on for some reason.(newbie)

You guys say jake rabby has don some testing on the topic.

I thought that most natural stuff ran cooler than syn. or tranfered the heat away from the motor better.

If there is evedence to the contrary please tell me.

I have done a ton of testing with synthetics and seen drastic improvements in oil temps with a couple of oils. I run synthetics in every one of my personal cars and have went as much as 18K on one oil change....

Royal purple and Valvoline took the cake in my testing.. More to come now that I have the datalogger and a second R&D only dyno on the way!

My '86 Toyota 4x4 truck just turned 299,900 miles. I use 1 to 3 or 2 to 2 ratio, synth / conventional. And I go 6 to 7,000 between oil changes. Seems like good stuff to me.

Ill chime in, My recent experiance is with a fairly low mile rebuild of the 2.0 in my Yeller 73. Has had Dino run in it since ..rebirth.
In prep for the Run down to WCC I decided to switch to Syn.
I used Castrol's 10-40 version.
No leaks 3K odd miles later after driving from North of Seattle to Socal, punting the car around the streets of Willow, then back to Seattle
Temps never got excessive (as measured by the Ultra-accurate OE console guage ) evan though we averaged 85-90mph all the way back!

Im stayin with Syn