I think you may have another problem not oil related. A diesel with good compression, a healthy starter and battery, and most importantly, fully functioning glowplugs should light off fine at those temps. Even with 15w-40. Mine will all light off at subzero temps on the first crank due to regular maintainence of the starting systems. I used to run petro oil but went to 5w-40 Delo 400 Synthetic which does seem to make starting less harsh at low temps. Check your starting system carefully. RT

It has always started perfectly (Like within the first 1-1/2 rotations) until the day after got some bad advice about puting a little dino oil in the tank to "help the IP lube" and get rid of "useless" oil in late December. From that day on, it will miss on 2 to 3 cylinders when I do a cold start, even after the block heater. When the engine is at operating temp, i don't even hear the starter motor as it starts so quick.

I ran the tank nearly dry to the point of the engine starting to sputter before filling up today. Hopefully that will get rid of the problem.

I don't know if I would dare run it to sputtering but I put a couple gallons of motor oil in my tank a while ago and 5 tanks later it was still there, that was until I finally ran it into reserve and filled it up. Quite something how much difference that little oil can make at an cold start or cold idle.

Did it affect your cold starts also? How did you get "couple gallons" ither without knowingly doing so?

The advice that was given to me was a quart per tank, 2Q/tank at most. "A Little goes along way."

Per the owner's manual for my '83 TD, 15W-40 is good for temps down to 23 F. Yet the owner's manual for my '87 TD sayd this weight oil is good for temps down to 5 F. I don't know if that's because it is a 6 cyl. vs. a 5 cyl. I would agree with the suggestion of using your block heater to help your engine out. Every car is different, especially when they get older. This when they start to develope their own characteristics. My first Benz, an '80 300SD needed to be plugged in when the temps got down to only 34 F. Then again, that car had 280,000 miles on her.

-30 C outside right now. Plugged in all night, 5W50 Syntech with a Slick 50 treatment every five oil changes.
Hawes fuel conditioner every tankfull to remove extra moisture and add lube. Condensation in fuel tanks is a problem not considered often - it happens more when temps are around the freezing mark.
With this set-up she starts everytime in one glo-plug cycle. This is in a 1.6 litre 4 cyl VW engine.

I would much rather worry about dents caused by falling coconuts - but hey - that's somebody else's problem.

Cheers

Well, this is quite a lively thread. Apparently I have good compression on all cylinders, between 350 and 370. I had this test done by a shop half a year ago. Glow plugs are less than a year old and I checked them maybe a couple months ago. I guess I should check them again.

I'm considering switching to Mobil 1 0W-40. Maybe it'll help, maybe it won't, but my logic says it'll reduce cold-start wear and protect better at high temps than regular 15W-40 oil. What do you guys think?

15W-40 oil is not your problem
 

Delvac 1300 15W-40 meets 10W cold pumping specs. This grade is adequate for your climate. Typical winter low temperatures in Reno are 20+ F. with the occassional dip to single digits.

Have you checked your battery's level of charge? Terminal connections at the battery and starter? The starter can very gradually slow down over time. Fast starter speed is essential in very cold weather.

A lighter synthetic oil may only temporarily solve your problem. Also, there is very little difference in 5W-40 and 10W-40 at 10 degrees F. Put some of each in the freezer and see for yourself.

My battery is only half a year old and it doesn't sound like it's low on charge. The starter spins fairly fast, though I'm not sure if it's as fast as a new one. It could be the starter's fault, but I'm quite sure lighter oil would help since the car starts perfectly when it's a bit warmer. I'm tempted to try the 0W-40. Too bad I can't find 5W-40 anywhere, other than the Rotella Syn which I don't trust. The 0W-40 is apparently used year-round by AMG vehicles and Porsches and it's CF rated, so I don't think it's a bad oil.

Mobil 0W-40 is an API SL gasoline engine rated oil that also meets the old CF rating. You can get much better for your diesel. Rotella T synthetic is now API CI-4 rated. There is no reason to be afraid of Rotella. Unless you live in an extremely cold climate group II and III oils are just fine. Since you are running a diesel you may as well have the latest spec CI-4. Better soot handling and high/ low temp deposit control.

I'm still suspicious of your battery and connections. I have a two year old battery. This fall I added water (about a quart) and put the charger on it at 6 amps. It took over 24 hours to bring to full charge. This improved starting at all temps.

Good luck, keep us informed on your progress.

It seemed to take longer to stabilize after starting but I didn't notice cranking time changing a whole lot. I knowingly did it, I probably will again next year (unless running WVO) but after it drops below 32*F it is time to clear the system out and run only diesel. Well the advice I read was don't exceed 20% oil which is pretty much 4 gallons and I only did half of that, no problems.

Last night I made the switch to Mobil 1 0W-40. Unfortunately I haven't been able to find out whether it starts better because it's a lot warmer right now. So far so good and I'll keep an eye out for leaks and such. I already had a small leak prior to the change. Oil pressure is still the same as with dino 15W-40 even when hot, but it seems to build up quicker after a cold start. For some time I was struggling in deciding between 0W-40 and 15W-50. I might try the latter in one of my other cars. The bottom line is I've decided to switch all my cars to synthetic.

Yukon, Slick 50 is bad snake oil. There are web sites devoted to the negative aspects of the stuff. DuPont (makes the mbte (sic)additive) recommends that it not be used in automotive applications. The teflon has been known to plug internal oil passages - ever scrapped teflon off of a high temp pot? As most of the threads state - additives in properly engeneered oil are generally a waste. Slick 50 and similar products would be helpful in a tooling machine etc. where unusual oil shear takes place but not in normal automotive use.

Yeah - I've heard all that and more. I have also been using the stuff for the past decade in domestic, Japanese and German vehicles with outstanding results. I believe it has saved me a great deal of wear and tear in sub-zero startups.

There are times when it is so cold the idiot light for oil pressure will stay on for a couple minutes on some folks cars - mine goes out in a no more than twenty seconds.

I have had best performance from Slick 50 about 10,000 miles following a rebuild on an engine when I treat the engine after it is well broken in. Compression remains high, yet turning it over at -30 is much easier than without the treatment.

I don't own shares in the company and I don't sell the stuff - I just use it and thank God I am not one of the unfortunate folks that have had a bad experience with the product.

Thanks for the heads up though.

Cheers

yukon, it's only a 'tropical' -15 deg C here right now , lol :)

i cannot imagine what -30 would do to my car , hehe. :eek:

what year/model is your vw?

i had a '79 rabbit diesel 5spd which is sorely missed.


regards -
bob (ex-pat canuck in freezing Mass. !)