I have used synthetic oils exclusively in everything from my outboard
(synth 2-stroke) to my Volvo (300,000+miles) to my Dodge Cummins Diesel
(290,000+mi) and finally my Honda mini van (187,000+mi) all with
original engines - none of them burn oil and all have near-original
compression.

The ONLY problem with using a synthetic in an older engine is that
between the oil's detergent/cleaning capabilities and slightly lower
viscosity, if the engine is prone to leak oil, it will. I figure if my
engine leaks oil, I need to fix the leak and I don't mind if the
crankcase gets cleaner.

With synthetic oil, ALL my engines and transmissions (I use synthetic
transmission fluid or gear lube as the case may be) run measurably
cooler. Cooler means less friction and better oil flow (better flow
spreads the heat around where it can cool more efficiently.)

I have only had good results with synthetic oil and from what I have
both read and experienced, it is far superior to Dino oil. Tests have
shown that synthetic oil does not break down nearly as fast and if kept
clean will far outlast other lubricants.

My dad always taught me that keeping the oil clean is equally as
important as which oil you choose you use to lubricate the engine with.
I use remote dual oil filters on all my engines, all with outstanding
results. Dad always said it's cheaper to replace a filter than to
replace a set of bearings. I think he was right, although now I don't
change the oil as often as I do filters, since I have seen convincing
evidence that synthetic engine oil can/will last 12,000 miles or more.
I change mine every 6,000 miles which lets me sleep at night. I change
filters every 3,000.

I have friends and relatives that have adopted the same procedure all
with the same excellent results.

That's my experience, your mileage may vary.

Jeff



jamesgangnc wrote:
I think a few people with high performance boat engines, like
supercharged tall deck big blocks, have similar high clearances and run
50 or 60 wt racing oil. Then people think if it's good for a racing
engine then it should be good for me. Not considering that they have a
completely different engine.

Gene Kearns wrote:
On 5 Jun 2006 20:03:26 -0700, wrote:

. Straight weight oils (even as thick as SAE 50) do not have the
?film strength? of multi-viscosity oils such as 5W-20, 5W-30, and
10W-30

This is opposite of what research I have done says and what I have
personally seen in aviation engines. Film strength of multi-viscosity
oils fails when the viscosity improver's fail under extreme pressure.
The oil molecules will re-link in the sump as they cool off, but the
damage to the metallic parts is done.

I would NEVER recommend multi-viscosity oils in extreme pressure
situations (barring really cold starts) and the valve train is a great
place to find such situations. I suspect the article's advice is
driven by people using way to thick an oil.... SAE 50 in an aircraft
engine is the standard... but then it has HUGE clearances compared to
a water cooled boat engine.