synthetic oil?

[swzhao]

Hi,
I have a subaru forester 2001. I switched to synthetic engine oil a
few years back in hope that the engine can run better and I can change
oil less often.
However, so far by my experience, the oil still gets very dirty after
5000-7000 miles and I still need to change oil by same interval as
before.
Is this well expected? Does synthetic oil really give me any benefits?

Another question: can I switch back to conventional mineral oil? Is
it safe to the engine?

Thanks,
Joshua

 

[Carl 1 Lucky Texan]

Hi,
I have a subaru forester 2001. I switched to synthetic engine oil a
few years back in hope that the engine can run better and I can change
oil less often.
However, so far by my experience, the oil still gets very dirty after
5000-7000 miles and I still need to change oil by same interval as
before.
Is this well expected? Does synthetic oil really give me any benefits?

Another question: can I switch back to conventional mineral oil? Is
it safe to the engine?

Thanks,
Joshua

Synthetic oil usually 'looks' bad because it does a superior job of
keeping 'varnish' dissolved/suspended. I have no idea if anyone has
determined that the varnich left on engine internals is harmful, but
synth. oil can dissolve it. It would look particularly bad from a
vehicle that had been using convetnional oils and/or with extended drain
intervals.

I doubt there would be any problem switching back.

Folks who fly planes or are responsible for fleet maintenance perform
regular OA (oil analysis). Several companies can do this for
individual's cars.

for more than you ever wanted to learn about engine oils, checkout
www.bobistheoilguy.com

Carl

 

[nobody >]

Synthetic oil usually 'looks' bad because it does a superior job of
keeping 'varnish' dissolved/suspended. I have no idea if anyone has
determined that the varnich left on engine internals is harmful, but
synth. oil can dissolve it. It would look particularly bad from a
vehicle that had been using convetnional oils and/or with extended drain
intervals.

I doubt there would be any problem switching back.

Folks who fly planes or are responsible for fleet maintenance perform
regular OA (oil analysis). Several companies can do this for
individual's cars.

for more than you ever wanted to learn about engine oils, checkout
www.bobistheoilguy.com

Carl

As an aside, my dealer uses Castrol part-synthetic for oil changes. The
mechanic told me (unofficially, of course) that it's safe for at least
10k miles as long as the filter is changed each time.

 

[swzhao]

10k miles no matter how dirty it looks like?

 

[Joe]

Synth is probably best for temperature extremes. If you change the oil
& filter as per the vehicle's maintenance schedule (with either synth or
dino), you can't go wrong. Just don't skimp on the filter.


(e-mail address removed) wrote in

 

[clare]

Hi,
I have a subaru forester 2001. I switched to synthetic engine oil a
few years back in hope that the engine can run better and I can change
oil less often.
However, so far by my experience, the oil still gets very dirty after
5000-7000 miles and I still need to change oil by same interval as
before.
Is this well expected? Does synthetic oil really give me any benefits?

Another question: can I switch back to conventional mineral oil? Is
it safe to the engine?

Thanks,
Joshua

Fully expected. Synth is only an advantage in extreme heat or extreme
cold. It does not thicken as much cold, or thin/break down/ sludge in
high temperatures.

My PT cruiser has a pretty tight hood area so I run synth to give the
engine a fighting chance in the heat - and it doesn't hurt in the
ontario winter cold either.
I still change it every 4 months ot 6000km

 

[nobody >]

10k miles no matter how dirty it looks like?

"Dirty looking" doesn't really count. I've been around oil sampling by
wurk's fleet services and have seen almost-black oil that tests fine for
anything that would damage the engine.

 

[Tony Hwang]

Fully expected. Synth is only an advantage in extreme heat or extreme
cold. It does not thicken as much cold, or thin/break down/ sludge in
high temperatures.

My PT cruiser has a pretty tight hood area so I run synth to give the
engine a fighting chance in the heat - and it doesn't hurt in the
ontario winter cold either.
I still change it every 4 months ot 6000km

Hi,
Today's oil is far advanced compared to years passed by. synth oil
every 6000km? You must have lots of money to waste. Is your car turblo
charged one? Even regular 5W-30 will last 10k Km in normal driving. Do
you replace spark plugs every 6 months too?, LOL!

 

[Joe]

Hi,
Today's oil is far advanced compared to years passed by. synth oil
every 6000km? You must have lots of money to waste. Is your car turblo
charged one? Even regular 5W-30 will last 10k Km in normal driving. Do
you replace spark plugs every 6 months too?, LOL!

If you don't change fluids as per the OEM schedule and the vehicle is
under warranty, you may jeopardize your warranty.

 

[mred]

Synthetic oil usually 'looks' bad because it does a superior job of
keeping 'varnish' dissolved/suspended. I have no idea if anyone has
determined that the varnich left on engine internals is harmful, but
synth. oil can dissolve it. It would look particularly bad from a
vehicle that had been using convetnional oils and/or with extended drain
intervals.

I doubt there would be any problem switching back.

Folks who fly planes or are responsible for fleet maintenance perform
regular OA (oil analysis). Several companies can do this for
individual's cars.

for more than you ever wanted to learn about engine oils, checkoutwww.bobistheoilguy.com

Carl

It all depends on how the car was driven ? Is that city miles or
highway? or a combination.

If its city miles with few highway miles , its not the colour of the
oil that will determine the oil change interval , but the accumulation
of acids and water in the oil.

A car driven mostly on the highway at highway speeds , (above 60 MPH,)
will burn off all water and acid in about 20 miles of this type of
driving , because the engine truly gets up to optimum operating
temperature.

In city driving the engine oil and engine seldom if ever reach the
same temps as when driven for long periods on the highways.

If you drive mostly in the city it would be adviseable to change the
oil& filter every 5000 miles

If your drivng is mostly highway you could probably go at least 7-8000
miles without a problem with full synthetic.

I change my oil every 5000 miles and I drive a 50-50 combo . of city
highway driving.(spring and fall)

After all, oil changes are cheap maintenence,and I use Mobil 1
synthetic 5w30 in the summer gray cap and yellow cap in the winter
(extended service)

Hope this helps?
Ed

 

[clare]

Hi,
Today's oil is far advanced compared to years passed by. synth oil
every 6000km? You must have lots of money to waste. Is your car turblo
charged one? Even regular 5W-30 will last 10k Km in normal driving. Do
you replace spark plugs every 6 months too?, LOL!

I drive my cars untill they are 18 years old, and then sell them.
Won't happen with 10,000 mile oil changes, particularly running
standard 5W20 or 5W30 oil.
I generally pull plugs every 50-60000km. This assures they WILL come
out. If they are still good, they may go back in. Seen too many that
may as well have been welded in at 110,000km.

 

[clare]

If you don't change fluids as per the OEM schedule and the vehicle is
under warranty, you may jeopardize your warranty.

ANd not only that, you can bitch and complain all you like after the
engine has "coked up" - if you have "neglected" your oil changes it's
YOUR pocket that hurts.

 

[Big Jim]

10000km= 5-6,000 miles

I drive my cars untill they are 18 years old, and then sell them.
Won't happen with 10,000 mile oil changes, particularly running
standard 5W20 or 5W30 oil.
I generally pull plugs every 50-60000km. This assures they WILL come
out. If they are still good, they may go back in. Seen too many that
may as well have been welded in at 110,000km.- Hide quoted text -

- Show quoted text -

 

[DJD58]

Hi,
Today's oil is far advanced compared to years passed by. synth oil
every 6000km? You must have lots of money to waste. Is your car turblo
charged one? Even regular 5W-30 will last 10k Km in normal driving. Do
you replace spark plugs every 6 months too?, LOL!

I have to admit, that I use fully synthetic Mobil1 on my Audi A4, and
change the oil and filter (using an OEM filter) every 5,000 miles.
Probably overkill but that's just how I roll..... ;-)

Dan D
'99 Impreza 2.5 RS (son's)
Central NJ USA