While discussion are on about fresh fuel mixing with old fuel i did a auto oil service and filter change on our small auto hatch a few days ago, total oil capacity is 5.6 lts. I didn’t think much about auto oil changes until 12 years ago as we did not keep our cars long enough to change the automatic oil twice.
If i just changed the automatic oil via drain plug and fitted new filter etc i would only have change 2.1 lts of the total oil capacity of 5.6 lts.
Doesn’t sound like a big deal, but changing the tranmission oil this way draining and refilling using just the 2.1 lts can be a problem long term. This 2.1 litres of new oil will be mixed with 3.5 litres of old oil, so the new oil (that is 100% of the 2.1 lts of fresh oil) will become 62.5 % fresh oil after first drain, 39 % after 2nd drain, 24 % after 3rd drain and after 4th drain my fresh content of oil in box would be only 15% new oil (and 85% old) these are aprox figures.
The best way to change all the oil (98% anyway) is to disconnect the return hose line running from cooler in radiator back to the transmission you can fully flush the transmission for a complete fluid change using fresh oil, if this line is flexible disconnect at tranny, if not disconnect at radiator end. Place a hose over this into a large container and get someone to add oil at filler hole as it is pumped out(place transmission in drive and leave idle) hopefully this will work.
I know another way which is the 10/10/10/10 method, which involves driving 10 klms then change oil, refill then drive another 10 klms and so on and so forth till you do the forth change, this will give you an end result of 89% fresh oil, but you would go thru 8.4 lts of auto fluid to do it?
If you go to an automatic transmission shop they will just do the standard auto service/filter etc, if you want it all changed they will do a full flush similar to above, but you will be charged an additional $80-$100 for the oil/work performed.
For preventative maintenance reasons a good additive works well between changes.
If i just changed the automatic oil via drain plug and fitted new filter etc i would only have change 2.1 lts of the total oil capacity of 5.6 lts.
Doesn’t sound like a big deal, but changing the tranmission oil this way draining and refilling using just the 2.1 lts can be a problem long term. This 2.1 litres of new oil will be mixed with 3.5 litres of old oil, so the new oil (that is 100% of the 2.1 lts of fresh oil) will become 62.5 % fresh oil after first drain, 39 % after 2nd drain, 24 % after 3rd drain and after 4th drain my fresh content of oil in box would be only 15% new oil (and 85% old) these are aprox figures.
The best way to change all the oil (98% anyway) is to disconnect the return hose line running from cooler in radiator back to the transmission you can fully flush the transmission for a complete fluid change using fresh oil, if this line is flexible disconnect at tranny, if not disconnect at radiator end. Place a hose over this into a large container and get someone to add oil at filler hole as it is pumped out(place transmission in drive and leave idle) hopefully this will work.
I know another way which is the 10/10/10/10 method, which involves driving 10 klms then change oil, refill then drive another 10 klms and so on and so forth till you do the forth change, this will give you an end result of 89% fresh oil, but you would go thru 8.4 lts of auto fluid to do it?
If you go to an automatic transmission shop they will just do the standard auto service/filter etc, if you want it all changed they will do a full flush similar to above, but you will be charged an additional $80-$100 for the oil/work performed.
For preventative maintenance reasons a good additive works well between changes.