Maintenance and FE

[groar]

I have been directed to page 9 of this : http://www.iea.org/Textbase/work/200...e/calwell2.pdf
It show % saving against the 3 phases of driving cycle.

A little search gave me this link : http://www.ataevents.net.au/tmc/spea...sh-Castrol.ppt
Slides 13 to 15 say that the main parameter for lubricant fuel economy is engine load.
As my observations are at idle, this is when the load is the smallest.

Denis.

[IndyIan]

I'm thinking your improvement is from having slightly thinner synthetic oil put in and the new oil filter. I don't really know how much hp an oil pump uses but pushing oil through a clean filter has to use less.
Even if your new oil isn't synthetic odds are it is still slightly thinner at higher temps than the old 10w40.
I run shell rotella T 0W40(diesel oil) in my ATV, its the only rotella T that is full synthetic, it might be available by special order through your mechanic? It says on the jug that its made for extreme climates like Canada but I'm sure the Alps can get just as cold.
Ian

[ATaylorRacing]

Before maintenance:

Bought a 152,000+ mile 3 cyl Geo Metro and drove it the 200 miles home. It got 46 mph vs EPA 49.

I took out 70 lbs, changed ONLY the plug wires, cap, and rotor. I aired up the tires to only 40 and put on homemade headlight covers. The FE is now 50-57!

Though the lighter wt helped, all of these trips involved carrying one way a set of Mustang rims (99 lbs), a set with tires (198), or even 2 full sets (396 lbs). With the 2 full sets acceleration was B A D ! The 1 full set would hurt the FE about 2 mpg.

I did not change the plus yet since it was only rough running at idle and smooth on the road.

When I do drive on open roads I go about 58-62 in 55 mph zones and 65-68 on the 70 mph zones....someday I should try an unloaded trip at only 55 or 50 to see how much better the FE can be...57.0 has been my best on three different trips. My car also gets better FE at the higher speeds compared to the 55 mph zones that involve going through a few small towns with slowing and stopping, even though I FAS. Pulse and glide makes worse FE in my car since it takes too much energy to get back up to speed.

[ATaylorRacing]

Originally Posted by ATaylorRacing

I did not change the plus.....

Should have read PLUGS!

[tasdrouille]

The air filter wont affect fuel economy like that, especially not a idle. I've put over 30k miles between air filter changes on my previous TDI without impact on fuel economy.

The oil change might have helped, but a >10% improvement in FE from switching oil is unheard of. Have you measured a difference in steady state driving under load?

[groar]

Originally Posted by tasdrouille

The oil change might have helped, but a >10% improvement in FE from switching oil is unheard of. Have you measured a difference in steady state driving under load?

My wife has the scenic since my Xmas challenge (we swap cars regularly) so I didn't drove it on my daily commute since. During my challenge I have seen 2.6L/100 instead of 2.8 at 80km/h and 2.2L/100 instead of 2.3 at 70km/h, but as it wasn't my daily commute I can't say if it's the same phenomenon or because I was on a little downhill my brain couldn't detect.

What is sure is that before the maintenance my wife was at 6.0L/100 and her last 220 km are at 5.3L/100 with colder temperatures. She has short commutes of 32 km round trip and does several smaller trips. I asked her if she changed something in her driving and she replied no.

I have to do the maintenance of the other car (4 years older : 97). The manual doesn't talk about 5W oils, only 10W and 15W. I'm wondering if I can use the same 5W40 oil. I'll ask the mechanic Friday.

Denis.

[groar]

Originally Posted by groar

I plan to visit my mechanic when he is back from holidays to know more about it and see the difference between his 10w and 5w oils. He insisted on the fact the 5w is more expensive and it was 20% more expensive. It may be some magic with some additives in this oil, or some magic from new kind of filter, or...

I saw the mechanic Yesterday and we talked about it. He didn't made anything else than what was mentioned : changed air & oil filters and oil. The 10W40 oil is a semi-synthetic one, while the 5W40 is fully synthetic.

He had no idea about what could have such an impact on fuel efficiency in idle. He was only afraid of the engine eating too much oil as they are using 10W on all engines except the newer with particles filters on which they use this 5W.

Yesterday the same mechanic did the maintenance of the megane, he changed air, diesel & oil filters and oil from 10W40 to 5W40. I'll see if this is confirmed with my wife's next tank in scenic and my next tank in megane I filled up today.

Denis.

[basslover911]

Well I changed the oil at 5,000 miles and nobody said anything about the oil being to dark so I am guessing that everything was good.

I am also adding a PVC catch can, we will see how much blow by oil I get between oil changes.

[Compaq888]

I remember when i bought my car I changed the spark plugs, spark plug wires, distributor rotor, distributor cap, pcv valve, some hoses, air filter and tightened the throttle cable. The car bogged in 5th gear anything under 32mph. After I replaced all that I could put the car in 5th at 25mph with no problems. It's very hard to identify what the problem is so it's best just to do the maintenance on the car instead of just driving it till the problem arises.