5w-40 synthetic in idi?

kevin g · Post by **kevin g** » Sat Jan 03, 2009 9:24 pm

Hello, I am having trouble finding a 5w-40 diesel oil for use in winter, that is non synthetic. Of course there's all kinds of 5w-40 and 5w-50 gasoline oil and (synthetic) diesel oil that the tdi's and newer diesels are running. Would it be safe to run this in an old high millage 1.6 idi jetta? I have never used synthetic before, is there anything that I should watch out for?
I was considering mobil1 5w-50 diesel synthetic

Vincent Waldon · Post by **Vincent Waldon** » Sat Jan 03, 2009 9:26 pm

Go for it... perfectly safe and you'll probably notice easier winter starts right off the bat. Many many years ago when synthetics were first introduced there were some issues reported with synthentics causing your seals to swell, shrink, your pets to go deaf, etc etc etc, but it all got worked out and you can swap back and forth without worry.

Just make sure it's diesel-rated... CI-4 or better is the current standard that matches the CD you'll find mentioned in the owner's manual.

The only time synthetic is not recommended these days is when you're breaking in a new engine... *too* slippery for that application.

kevin g · Post by **kevin g** » Sat Jan 03, 2009 9:34 pm

That's just what I wanted to hear!!

Thanks!
My motor does use a bit of oil, should I expect this to increase with synthetic?

libbybapa · Post by **libbybapa** » Sat Jan 03, 2009 10:29 pm

If it's using oil from leakage, it might increase. If it is burning it, it might actually decrease as synth tends to have a higher burn point but you'd have to check the specific oil's spec sheet and compare it to your current oil. Probably easier to just give it a go.

Andrew

tylernt · Post by **tylernt** » Sun Jan 04, 2009 12:53 am

I've gone back and forth between full-synth 0W40 and dino/synth blend 10W40 with no problems leaking or otherwise.

I can't seem to find straight-dino diesel-rated oil anywhere locally.

surfcam · Post by **surfcam** » Sun Jan 04, 2009 2:07 pm

I put Amsoil 5W-40 full Synthetic Premium Diesel Oil and 3 micron bypass filter set-up into my Jetta about 10 year ago. The car had about 200,000km on it at the time. It leaked out of every seal. The clutch even started slipping. I was not happy. I changed it back to dino 15-40 and the leaking subsided. There's an adapter plate that goes where the filter was and is also problematic. I had to replace the fittings with Airoquip fittings to make it work. I think his sett-up is made for bigger trucks. Now I have two big filters sitting right over my tranny. They get in the way just as much as the A/C the car has.

kevin g · Post by **kevin g** » Sun Jan 04, 2009 9:18 pm

Ok, today I changed the oil with synthetic 5w-40 mobil 1 diesel, so far so good but I haven't put many miles on yet. Surfcam mentioned that he had many leaks with synthetic so I will be watching closely for that!
I will be looking forward to the easier cold starts

kevin g · Post by **kevin g** » Sun Jan 11, 2009 12:03 pm

I have put about 700 miles on my 5w-40 mobil1 synthetic in my jetta. I am already starting to notice that it is leaking a bit more with synthetic. Still nothing serious but definitely worth noting. But it doesn't seem to be using any more oil than it would with dino grade. And I definitely starts much easier in the cold temperatures

So im happy with it, just going to keep a close eye on any leaks to see if they get any worse.

Golf/Jetta · Post by **Golf/Jetta** » Sun Jan 11, 2009 5:35 pm

i find 0W40 synth makes my turbo whistle on cold start up's and go's (one of the don't do's) and leaks a little out of the valve cover. i do still use this oil in winter, just don't have the time to wait and get a boost..

JRM · Post by **JRM** » Sun Jan 11, 2009 6:03 pm

i use synthetic in all of my engines except my high mileage toyota and Vw diesel, i swapped both over to synthetic and had the exact result as surfcam did in both my toyota truck and vw diesel. i have now put both back to dyno and the leaking and oil useage stopped.

surfcam · Post by **surfcam** » Sun Jan 11, 2009 9:12 pm

I have heard that if you have been running dino oil for 200,000km or more and switch to synthetic it is sometimes problematic. Some synthetics have way higher amounts of detergent in them. This will clean out the coking and dino sludge witch causes leaks. To make matters even worse this oil is a lot finer so it will find its way out of the engine a lot easier. Starting your engine with synthetic after break-in oil would be the best way to go.

kevin g · Post by **kevin g** » Sun Jan 25, 2009 11:20 pm

2000 miles now since switch to synthetic. Definitely burning more oil than dino. I will keep using it for the quicker cold starts until it warms up then switch back to dino.