How to improve your fuel economy without realy trying
  • Help
Results 1 to 13 of 13
  1. #1
    Member martook's Avatar
    Join Date
    Jul 2012
    Location
    Coomba Park NSW
    Posts
    90

    Default How to improve your fuel economy without realy trying

    Hi all, my 03 C5 (2.0 ltr petrol) has returned an average of 7.7 ltrs/100klm for the last 60,000k best was 7.6 & worst was 9.9(sydney traffic) now suddenly its 7.1 ltrs/100klm & all i did was change the transmission oil!! just did a 900 k trip, some freeway @110/100 some back roads inc 2 mountain ranges(2nd gear) & it flipped up to 7.2 & then went back to 7.1 & i'm still on the same tank "I'M RAPPED"
    cheers
    Brian

    Advertisement
    2008 ford Mondeo 2ltr turbo diesel + 6 speed alsin g/box
    1979 cx c-matic
    1977 cx 5 speed
    2000 peugeot 306 convertable
    1978 peugeot 604 sl
    2005 c5 (wrecking)
    2003 c5 auto (wrecking)
    2001 c5 5 speed
    1960 Renault floride under restoration

  2. #2
    Fellow Frogger! deesse's Avatar
    Join Date
    Dec 2010
    Location
    Melbourne Australia
    Posts
    571

    Default

    tell me more Brian. It is an auto I presume. How did you change the tranny fluid? The transmission is sealed for life. My mechanic won't do it. I certainly wouldn't know where to start. I have read posts on how to do it and apparently you can only empty out about half which you have to do a few times to get it 95% new. But I have also heard that it makes a big difference and the transmission lasts much longer before giving up the ghost prematurely. So any tips would be good. (I have a 03 C5 2 litre petrol auto wagon)
    cheers Tony

  3. #3
    Member martook's Avatar
    Join Date
    Jul 2012
    Location
    Coomba Park NSW
    Posts
    90

    Default

    Hi Tony,yes it's an auto just clicked over 100,000ks so i decided to change the fluid, it's straitforward you can only get 2.25 ltrs out each time you drain it so i did that 3 times = about 7ltrs,drove it a few ks between changes,first lot was dark grey was clearer by the 3rd change
    i did this to hopefully extend the life of the auto box, the fuel economy result was unexpected. i brought a 20ltr drum of the oil & intend doing another change in about 20,000ks,you must use ATF71141 oil & i think it's back in stock from Mobil, when i brought mine Mobil was out of stock but Imperial oil had stock,a lot cheaper in 20 ltr drums. To drain it simply remove the drain plug which has 2 hex nuts, the inner is a level plug & the outer drains the box & to fill it remove a square drive plug on the top of the box add fluid till it comes out the level plug.most of the oil stays in the converter so that is why you can only get about 1/3 out each time.
    cheers Brian
    2008 ford Mondeo 2ltr turbo diesel + 6 speed alsin g/box
    1979 cx c-matic
    1977 cx 5 speed
    2000 peugeot 306 convertable
    1978 peugeot 604 sl
    2005 c5 (wrecking)
    2003 c5 auto (wrecking)
    2001 c5 5 speed
    1960 Renault floride under restoration

  4. #4
    Tadpole
    Join Date
    Jun 2013
    Location
    Dee Why
    Posts
    23

    Default

    I presume that these boxes have lock up torque converters. This is to increase fuel economy. It is possible that your "old" oil was either the wrong spec, was left in too long or was contaminated and was not allowing the torque converter lock up to function correctly. Other possibilities are slower (slipping) gear changes and gear change point being different with the old oil. You would notice this and, also, if you are finding a fuel economy improvement on long trips, it is far more likely to be the torque converter lock up. Gear changes are not a significant factor in such use.

    While I know nothing about the details of the C5 auto box I do have some knowledge of oils. I think I can state that no oil turns grey with use of its own volition. Oils oxidise. In the case of Automatic Transmission Fluids they turn from a clear red to a more amber shade and eventually to dark brown then black, if taken to extremes. As they oxidise they may begin to smell, initially of "burning" and eventually of odorous sulfur compounds.

    A grey colour can indicate some water being present but this usually looks more cream than grey. Much more commonly, greyness indicates the presence of fine metal particles.

    Is the transmission oil taken through the radiator for cooling? If so, water could possibly be a factor but usually, because of the pressure differences, the ATF leaks into the radiator not vice versa. Metal from wear is unfortunately far more likely if the old oil was definitely grey.

  5. #5
    Fellow Frogger! IE23's Avatar
    Join Date
    Jan 2011
    Location
    Melbourne
    Posts
    749

    Default

    wow good thread, reminds me I should change my oil next service. I want the transmission to not only operator well but to last as long as possible.


    Adrian

    _________________

    Current;

    Xantia V6 Exclusive Auto 2000


    Past;

    CX25 GTI Turbo series 1 1985
    DS23 IE Pallas 5sp 1974
    CX25ie Pallas Auto 1984 Parts
    2CV 1988
    CX25ie Pallas Auto 1984

  6. #6
    Real cars have hydraulics DoubleChevron's Avatar
    Join Date
    May 2000
    Location
    Ballarat,Vic,Aust.
    Posts
    16,754

    Default

    It sounds like your trusting the trip computer ..... I'd suggest checking it tank to tank. I can't say I have much faith in trip computers

    ie: fill the tank, drive until empty, then fill the tank and see how much fuel it takes to fill.... and work out your mileage given the distance you traveled.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/citro%EBn-forum/90325-best-project-car-you-have-ever-seen.html
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  7. #7
    Member martook's Avatar
    Join Date
    Jul 2012
    Location
    Coomba Park NSW
    Posts
    90

    Default

    Hi, gear points are different now the box changes more, i agree the improvement is likely from better torque converter lock up. The AL4 auto is electronic controlled & "sealed for life"& thats the problem, the oil degrades & rapid wear occurs. my oil was grey/black,no sign of water & no smell,there is no external cooling the oil is cooled by a heat exchanger in the auto box connected to the engine /radiator system this means you can only remove the oil in the sump (about 1/3 or 2.25ltrs) each time you remove the drain plug. ATF71141 is yellow/honey in colour when new. hindsight is now showing that "sealed for life" is incorrect and oils wear out.
    regards Brian
    2008 ford Mondeo 2ltr turbo diesel + 6 speed alsin g/box
    1979 cx c-matic
    1977 cx 5 speed
    2000 peugeot 306 convertable
    1978 peugeot 604 sl
    2005 c5 (wrecking)
    2003 c5 auto (wrecking)
    2001 c5 5 speed
    1960 Renault floride under restoration

  8. #8
    Fellow Frogger! XM Mechanic's Avatar
    Join Date
    Aug 2004
    Location
    Sydney, Australia
    Posts
    308

    Default

    There is a link in the following thread with detailed instructions provided by Richo on how to change the oil.

    Please re-post C5 AL4 transmission refilling guide
    Regards,

    Garth.


    Fixin' Cit's.

    '19 308 GTi
    '15 DS 5
    '74 GS Convertisseur

    In the family
    '51 Traction
    '08 C5 X7 V6

    Previous ownership
    '95 XM V6 Series 2
    '96 306 XTDT

  9. #9
    Fellow Frogger! IE23's Avatar
    Join Date
    Jan 2011
    Location
    Melbourne
    Posts
    749

    Default

    Bearing in mind that "sealed for life" in Euro terms is about 3 years or the life of warranty. After that its in the interest of car manufacturers for obsolescence to take immediate effect. "Sealed to prevent service", would be more appropriate


    Adrian

    _________________

    Current;

    Xantia V6 Exclusive Auto 2000


    Past;

    CX25 GTI Turbo series 1 1985
    DS23 IE Pallas 5sp 1974
    CX25ie Pallas Auto 1984 Parts
    2CV 1988
    CX25ie Pallas Auto 1984

  10. #10
    JBN
    JBN is offline
    1000+ Posts JBN's Avatar
    Join Date
    Nov 2010
    Location
    Sydney
    Posts
    8,528

    Default

    Sealed for life is what it means. When the oil degrades to such an extent, the auto box fails (dies) and needs to be replaced. Citroen make it easy. The depreciation is such that when the auto box dies, you just junk the whole car and get another. Both my BXs were disposed of (for free) because the auto box died.

    The current problem with my Xantia is that the drain plugs (particularly the transaxle one) are starting to round off (internal hex Allen keyed). I rang ZF Australia but they don't supply them to the public. I rang their distributor in NSW but they just fobbed me off to an automatic transmission specialist who was asking me what size the drain plugs were, even though I told him which gearbox model it was. Typically I drop 2.4 litres every 10,000 kms when I changed the engine oil. That will extend out until I can get another couple of drain plugs.

    John

  11. #11
    Member
    Join Date
    Mar 2013
    Location
    Melbourne
    Posts
    86

    Default

    @Shane. Yes, trip computers are wrong. Both of them. They both show 11-11.5 in city driving for a 2.2 diesel over time. By actually using the on dash resettable kilo counter (the one that's part of the speedo) I have calculated a touch less than 10. A trip to heathcote and return recently returned a reading of around 7.0. I doubt a petrol could beat this. My old Xantia ran at about 8 in the country and 10 in the city.

  12. #12
    Member martook's Avatar
    Join Date
    Jul 2012
    Location
    Coomba Park NSW
    Posts
    90

    Default

    Quote Originally Posted by DoubleChevron View Post
    It sounds like your trusting the trip computer ..... I'd suggest checking it tank to tank. I can't say I have much faith in trip computers

    ie: fill the tank, drive until empty, then fill the tank and see how much fuel it takes to fill.... and work out your mileage given the distance you traveled.

    seeya,
    Shane L.
    Hi Shane 895ks on a full tank & the computer is saying 157ks to go, going shopping tomorrow round trip 98ks will take a 5ltr jerry can! its never done more than 800ks before Brian
    2008 ford Mondeo 2ltr turbo diesel + 6 speed alsin g/box
    1979 cx c-matic
    1977 cx 5 speed
    2000 peugeot 306 convertable
    1978 peugeot 604 sl
    2005 c5 (wrecking)
    2003 c5 auto (wrecking)
    2001 c5 5 speed
    1960 Renault floride under restoration

  13. #13
    Tadpole
    Join Date
    Jun 2013
    Location
    Dee Why
    Posts
    23

    Default

    Interesting that Esso/Mobil has not dyed the ATF71141 red. Makes no difference to its performance but it has been a tradition since the very first ATFs were introduced in the late 1940s. The idea was to be able to differentiate a gearbox oil leak from an engine one.

    The challenges for a sealed-for-life ATF are chemical stability (resistance to oxidation at elevated temperature), viscosity stability and friction coefficient stability. You are right, eventually all ATFs will deteriorate. The 71141 is apparently made from synthetic base oil to give good inherent oxidation resistance and to minimise the need for inclusion of viscosity index improvers, but it will not survive for ever.

    Your approach of part draining and refilling is appropriate I think. It is not possible to do a 100% drain as only the gearbox portion drains, not the torque converter. 25,000kms should be a very safe interval. The oil colour will tell you if you have left it too long. The drained oil should be, at most, only slightly darker than the fresh oil. Anything towards amber or black is bad news. If it happens with an oil such as 71141 then the box has a problem. It is running too hot, at least in some part of it.

    Re water, I asked if the oil was run out to the radiator for cooling. From what you say, the water is brought to the box. Either way, there is the potential for a leak between the two systems if there is a crack. However, the colour you describe doesn't seem like water-sourced. A very simple test is to heat a length of thinnish wire, or some similar steel item, in a flame and then put its tip into the drained oil. You will hear a definite crackle if there is even a trace of water. It is a very sensitive test.

    Final suggestion is that when you drain the box, keep a track of how much oil comes out. Make sure that the amount needed to refill it is similar to what was drained. Getting the level right in auto boxes can be a bit tricky. They don't like running low on oil and aren't that happy when overfilled.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •