1st timer

I changed to mobil1 yesterday and the mechanic told me that my car will be burning oil soon because i switched to synthetic at such high mileage(80000km)
tell me he's wrong!!!

pmptx

OK, he's wrong. The thought is that the synthetic will celan out all the gunk which has been plugging any leaks or sela issues. It is bunk.

optomos

Usually no, but at 50k miles there should be no problem whatsoverver! I switched to amsoil synthetic at over 100000km & still havnt used a bit of oil. It was normal on the older vehicles of the past, but with the curent oil & mechanical technology that has changed.

MikePA

Amazing how long this incorrect information hangs around. Might want to find another mechanic.

AMSOILs own web site indicates that some engines actually see REDUCED oil consumption.

Will AMSOIL Motor Oils decrease oil consumption?

Yes. When used in mechanically sound engines, AMSOIL Motor Oils can reduce oil consumption. Under test conditions, a reduction of as much as 42% was demonstrated for prolonged periods. However, this should not be taken to mean that AMSOIL Motor Oils are “cure-alls” for engines that consume oil because of mechanical problems.

fsttyms1

hes wrong. if you dindt burn any before you wont now. i swithched over at 100k Miles and im at 185k now on 15k change intervals and i dont use a drop.

SK2003TypeS

Agreed, he's wrong. Maybe the hidden agenda is to keep you on conventional oil to get you in to the shop more frequently.

optomos

The mechanic is probably from the old school of thought.

VTEC11

And also, I don't think 80,000km is considered high milage.

fsttyms1

probably. when syn firs came out you wernt supposed to put it in high mileage engines and once you went to syn you wernt supposed to go back

brakejob

group IV oils tend to shrink rubber, which was the thought on why syn causes leaks in high mileage cars...

older synthetics were plagued by this problem, but amsoil/mobil 1/many others blend their group IV oils with Group V (amsoil/mobil 1) or with group III (castrol syntec / quaker state) to negate the shrinking effect....

redline is all Group V oil, but hey, who is counting heheh im biased

1st timer

Wow! You guys made my day.

SodaLuvr

The first time you use synthetic, it is not uncommon for the engine to have some elevated oil consumption, but it will drop by the second or third interval.

For any car that has over 40,000 mi, I usually suggest Auto-RXing the engine prior to switching to ensure good ring seal, and that the seals have been properly cleaned and condition, reducing the chance of abnormal consumption or leaks.

Michael

SodaLuvr

No, the reason why syns can cause leaks in higher mileage cars is because the syn will often clean away dirt that is allowing a seal to "seal." Thus, before using syn, you were basically getting a false seal.

If use Auto-RX twice on a higher mileage car (100K+) prior to switching, you will greatly minimize the chance of leaks or excessive consumption.

I just recently switched a truck with over 160K on it to RTS 5w-40 after running two Auto-RX treatments; truck currently has no oil consumption or leaks.

Michael

brakejob

thats a reason, but group IV's do have a tendancy to shrink rubber... blending helped to counteract that...

SodaLuvr

I'd like to see some proof of that before I buy into it.

Michael

1st timer

What is it that you do exactly with this Auto -RX? But it's too late for me,I already switched to Synthetic with 50k on my car.