fuel economy,oil filter,oil type,fuel additive

dieseldave11

Well-known member
Joined
Mar 24, 2012
Location
Atlantic City New Jersey
TDI
2002 Jetta
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

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
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 CF-4 is an outdated standard - T6 meets standards that have superceded CF-4.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

Well-known member
Joined
Mar 24, 2012
Location
Atlantic City New Jersey
TDI
2002 Jetta
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 CF-4 is an outdated standard - T6 meets standards that have superceded CF-4.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

Veteran Member
Joined
Oct 13, 2011
Location
Dunnville
TDI
88 Jetta Diesel - 2000 Jetta TDI - 04 BMW M3 - 06 Kia Rio - F350 Superduty - 87 Buick GNX - Mobile Cranes
I agree with GoFaster Stick with what VW recommends for your engine 5W40 get a quality filter from a manufacture like MANN
 

slamhouse

Veteran Member
Joined
Oct 3, 2011
Location
Stanwood, WA
TDI
2006 Jetta TDI SE
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

Top Post Dawg
Joined
Sep 3, 2005
Location
Ohio USA
TDI
NB TDI, 2002.5, Silver
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.
 

jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
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.
 
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