Buying an old diesel

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Jan 3, 2020
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Location
Brittany
Last diesel car i had was back in 2017, The E250 is now only driven by my dad but i still service it. I recently bought another gas W124 but it's a 4 cylinder gas guzzler and it gets old quickly when you have to drive 500 km each week. A diesel would make sense and for the first time i would be ok with buying something else than an old Mercedes, Probably and Audi A4 B6 or Passat B5. I would like to be able to run WVO too, in a 50/50 mix. What are the most reliable diesel engines that can take WVO for many many miles? The reason i'm thinking about an Audi A4 is because i test drove one and was impressed by the torque and the fuel economy. 45+ MPG is doable. The interior was very nice too with woods and leather. What is your experience with specifically these diesel cars? What else would you recommend?
 
Ive bought three diesel cars and a diesel truck in the last year. A w140, two w124 cars, and a dodge 5.9 CTD.

Youre not going to do better for a long lasting quality diesel than a Mercedes. I’d drive either of my w123 cars across country tomorrow. The w124 feels lighter, and even with similar hp to a w123 300d, it feels faster and is more efficient.

I get 36-38 mpg in my 91 300D 2.5 turbo (602), and 26-28 mpg in my 93 300sd (3.5L 603). I’m a big fan of the 692 w124. It’s a little less substantial of a car than a 123/126/140, but excellent in every way.
 
Similar to ZR2, I had a '92 300D 2.5 Turbo, but got 32 mpg highway and 28 around town. Ran it for 248k miles.
If you change to bio-diesel or WVO, you'll have to replace all the rubber fuel lines, including the injector return lines, with Viton or they'll dissolve.
FWITW; people in the US buy old MBs to convert to WVO and usually only get 20k to 30k miles before the engines are destroyed. The rings and EGR coke up and goodbye.
 
The two diesels i had were a W124 (OM605) and a W202 (OM601) and i agree that they will be hard to beat... I've seen a lot of carnage due to WVO on some french forums. As you say, coked rings and scrapped liners are often the outcome but i wonder if there are ways to avoid that.
 
"... i wonder if there are ways to avoid that."
Maybe the newest synthetic oils will keep the rings cleaner and handle the sludging better. 20 some years ago when I was looking at WVO, mineral oil was the choice lube. EGR is a simple block off on the older MBs and the computers didn't do much.
Good luck with you project!
 
Maybe the newest synthetic oils will keep the rings cleaner and handle the sludging better. 20 some years ago when I was looking at WVO, mineral oil was the choice lube. EGR is a simple block off on the older MBs and the computers didn't do much.
Good luck with you project!
Worth investigating! As i said, a VAG product with a TDI engine from the early 2000s is ultra cheap here, perfect for experimenting.
 
I am doing a bit a research about the Passat and it seems like they have more problems with suspensions parts wearing out early... Something i've noticed is that other than a few squeaky bushings, balljoints and worn struts on the high mileage cars, i never had any failure with the W124 and W202 suspensions, far less than people around me with mostly PSA, VAG or Renault.
 
Make sure if you do buy a PD VAG it’s one without balance shafts as the drive key way wears out and ends up in loss of oil pump drive.

Personally I would not run WVO I would be looking at waste engine oil. Buy a centrifuge to remove the water and any solid particles. I would advise fitting a exhaust temp probe and gauge so you can monitor temps.
 
I would not buy a diesel for economics. For desire yes but saving fuel nope.
Agreed diesel fuel is substantially more expensive than gasoline and it's getting worse, 20% better fuel economy is pointless if diesel fuel is 40% more expensive.
 
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