fuel economy,oil filter,oil type,fuel additive

dieseldave11 · March 28th, 2012, 20:21

my fuel economy has decreased alot since I bought my car (02 jetta tdi) I was getting about 45 mpg now I am getting about 40 max but mostly 36, I need an oil type to put in my car that will get me great mileage, I looked at the t6 rotella today but it didnt say it was CF-4 certified on the 5w40, I also look at mobil 1 10w40 high mileage oil would either of these work or increase fuel economy? what type of oil filter does an 02 jetta use? and are there any fuel additives that I can add to my diesel tank to increase mpg? thanks alot!

GoFaster · March 28th, 2012, 20:29

Rotella T6 is suitable. CF-4 is an outdated standard - T6 meets standards that have superceded CF-4. (Your owner's manual can't automatically re-print itself when this happens ...)

Do NOT use the Mobil 1 10w40. That is meant for gasoline engines. It is not primarily meant for diesel engines.

But it is rather unlikely that the type of motor oil has anything to do with the fuel consumption. There is no magic fuel additive that miraculously improves fuel consumption. Weather, driving patterns, winter versus summer fuel, tire inflation pressure, etc have much more relevance.

dieseldave11 · March 28th, 2012, 20:45

Quote:

Originally Posted by GoFaster

Rotella T6 is suitable. CF-4 is an outdated standard - T6 meets standards that have superceded CF-4. (Your owner's manual can't automatically re-print itself when this happens ...)

Do NOT use the Mobil 1 10w40. That is meant for gasoline engines. It is not primarily meant for diesel engines.

But it is rather unlikely that the type of motor oil has anything to do with the fuel consumption. There is no magic fuel additive that miraculously improves fuel consumption. Weather, driving patterns, winter versus summer fuel, tire inflation pressure, etc have much more relevance.

so rotella t6 5w40 is good? what about 0w40 or 0w30?

what type of oil filter?

Dieselducky · March 28th, 2012, 20:45

I agree with GoFaster Stick with what VW recommends for your engine 5W40 get a quality filter from a manufacture like MANN

slamhouse · March 30th, 2012, 18:30

When's the last time that the timing belt was changed? and how many miles are on the new belt?

What happened to your fuel economy once the belt was changed?

How many miles are currently on the car?

Joe_Meehan · March 31st, 2012, 05:06

It sounds to me, like you are expecting a lot from a change in oil type. As long as you are using an oil that meets VW's specifications for your car you are not going to find much improvement in mileage due to oil choice or additives. Maybe some, maybe be even enough to measure, but likely not enough to get excited about. Using non-approved oils are more likely to cause you problems, maybe expensive problems that will make any milage gains look extremely small.

A change in oil type is just not going to make a meaningful difference.

williamgd2 · March 31st, 2012, 09:27

I have found that good fuel is where I get my millage.Try finding a good Qaulity fuel dealer and watch your millage go up.

jettawreck · March 31st, 2012, 18:14

Quote:

Originally Posted by Joe_Meehan

It sounds to me, like you are expecting a lot from a change in oil type. As long as you are using an oil that meets VW's specifications for your car you are not going to find much improvement in mileage due to oil choice or additives. Maybe some, maybe be even enough to measure, but likely not enough to get excited about. Using non-approved oils are more likely to cause you problems, maybe expensive problems that will make any milage gains look extremely small.

A change in oil type is just not going to make a meaningful difference.

Exactly.
And I would not use 0w-30 in a VW diesel except under continuous extreme cold conditions, in which case mileage would not be a priority.
As Joe said, you won't bring back "lost" mileage with a change in engine oil viscosity type.