Synthetic Oil Bad for Highmilers?

My mehanic claims that synthetics are very high detergent and are bad
to start using on old engines. My 87 Accord has 188,000 miles. He
said if it had had synthetic in it regularly before 100,000 miles it
would be fine. He reccommends using some of that seal swelling high
mileage stuff, but I'm hesitant to use anything that would soften the
old seals. Also he says the Honda oil filters are probably a waste of
money. He says he's not sure, but he knows the US aotomakers charge
too much for their filters. Don't filters need to have ratings like
engine oils.

 

Find another mechanic.

 

I agree. You have been using detergent oils all along so the detergent in
synthetics isn't going to make any difference. However if it is still in
good shape at 188.000 miles then why change what you have been using. You
aren't going to get any improvement........

 

If you have a 188K mileage machine, stick to dino oil and just change it
every 5K and you'll be fine. Use one of the better brands such as
Castrol or Valvoline. I think that extended use of synthetics in
internal combustion engines is counter productive because of the
extended time between oil changes.

However, synthetics in transmissions and differentials are totally in
order and I would not use anything else...

JT

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if its not leaking now, just use what youre using. it seems to be
working great so far.

 

How old is your mechanic?! I haven't heard this argument since the 50's
or 60's when detergent oils were new. Same deal concerning multi-grade
vs. straight oils, e.g., SAE 30. There are always 100's of "reasons" not
to use new things.

PS: What difference is the 100,000 mile mark supposed to mean?

 

I once wrote to Mobil about using synthetic in older vehicles. They said
that if you have leaks, the synthetic will leak more. They said that it
will leak through cork gaskets. They said it would be good to use as long
as your seals are good and not leaking.

 

Yeah, that's what he was saying. If the car had had syn all along it
wouldn't make any diffrtrence, but that the gaskets age according to
the oil that is used. He told me that if I used syn it would find all
my leaks.