Questions and Answers

Diesel vs Gasoline Engines: Comments Q. i read an article with some misleading information, Diesel Engines vs Gasoline Engines and i don't know when this article was written but i own a jetta TDI, oil changes are at every 10,000 miles this is not an 8L diesel its a 1.9L diesel, and diesel fuel is getting cleaner by the day due to the new emissions standards that diesels must pass, and fuel filters must MUST be changed every 20,000 miles due to the pump injection tolerances for foreign matter in the fuel.

As for cold weather starts, i have started mine at well under 10 degrees with out the aid of a block heater, and glow plugs should be replaced when you get a MIL light for the glow plugs (malfunction indicator light), because the systems on the newer 2000-06 VW TDIs constantly measure the resistance of the glow plugs and at the first sign of the resistance values going out of speck it will let you know. and for the thicker oil, VW TDIs use 5W-40 isn't quite so thick, and ive even heard of people who have started there TDIs model years 95 and up in -20 degree weather with no aids and they started up first try. so next time when talking about diesel passenger cars, consult www.tdiclub.com just thought i would let ya know.

Aaron

A. I don't understand what you find misleading. Is there something wrong with recommending changing the oil in any kind of engine every 3,000 miles? If you look in your owners manual you will see the 10,000 mile interval is for "normal service". That means clean dry roads with no turns or hills. The only person I know who drives in that category is the old lady who lives across the street from me. Most everyone else is in the "severe service" category, in which case you cut the service by, at least, half.

Volkswagen does recommend 5W-30 in the summer and 5W-40 in the winter. Says so right here in the Volkswagen Jetta service manual Volkswagen sent me. But then again, they want you to buy a new Jetta every couple of years also. Logic dictates that a gasoline engine that is under a lot less stress than a diesel engine and uses a light oil, the diesel engine would need a heavier oil to cope with the heavy stress a diesel engine endures.

By the way... tell your buddy there is a block heater for a Jetta diesel. He can get it at any Volkswagen Dealer.

Diesel fuels may be getting cleaner, but it will never be as refined or as "clean" as gasoline. If it were, it wouldn't be diesel fuel now would it?

Same question with the filters... Something wrong with recommending replacing them once a year? The average person drives 15,000 miles a year and Volkswagen recommends 20,000 miles under light service, so I don't think it's an unreasonable service interval.

In my neck of the woods it can get down to -40°. Would you risk your vehicle not starting when it's so cold your breath freezes in the air? My Mercedes will start with little or no problem at -10° without a block heater, but it sure feels good to know that the heater is plugged in and there is NO question it will start and have heat almost immediately.

But you're right, you don't need a block heater. Chances are the car may start without one. I bet you like to go to the casino and shoot craps too.

Now let's talk glow plugs. You will need to show me the wiring diagrams for the glow plug circuits and how they are checked by the PCM. Volkswagen must have left them out of the service manuals they send me. The glow plug codes I think you are referring to are:

• P1616 18024 Glow Plug/Heater Indicator Circuit Short to B+
• P1617 18025 Glow Plug/Heater Indicator Circuit Open/Short to Ground
• P1618 18026 Glow Plug/Heater Relay Circuit Short to B+
• P1619 18027 Glow Plug/Heater Relay Circuit Open/Short to Ground

They could... possibly... maybe... indicate four bad glow plugs, but they would never indicate one or two bad glow plugs. In short, the PCM can NOT measure the resistance of a glow plug, it never did and never will. So whoever told you it did was either lying to you or has no idea of how the glow plug system works.

Again, replacing the glow plugs every two years is not unreasonable at all. And on this schedule I replace them when it's a balmy 72° out, not when it's -10°. Why wait for them to go bad, isn't a little preventative maintenance better than a lot of repair? And I bet you wait for the timing belt to break before replacing it.

Now I'm sure you and your friends in that club are nice guys. They may even have a basic understanding of the principles of how a diesel engine works. But if it's okay with you, I'll keep going right to Volkswagen if I have a question about their cars, not a bunch of guys swilling beer in somebodys driveway.

Next time you write me, leave out the heresay, incorrect information and innuendo. Just thought I would let you know...