OT GM AND SYNTHETIC OIL

I WAS CHATTING WITH A BUDDY OF MINE LAST WEEK AND HE HAS A 1999 Chevy Blazer
which he bought in 2000.

He told me that his factory warranty states that synthetic oil cannot be
used in this vehicle or the warranty is totally invalid.

Has anyone heard of this before with any manufacturers vehicles ?
ed/ontario

 

Ed,

Good to see you back on the newsgroups again.

I have a 2001 Buick Century and there is no mention in the manual about NOT
using Synthetic oil. The only requirements are to use an GF3, API SL based
oil with a 5W30 viscosity. As a result, I use Mobil 1 5W30 year round.
Coming this summer, I might switch to the 10W30 grade since I don't need the
cold protection.

 

Cold protection?? 5W is for cold "protection", 10W is a heavier grade for

 

that's what he said.

 

Yup. 5W30 in the Winter, 10W30 in the Summer?

 

In

It's hard to tell from here which of you is yanking the other's
chain. Circle jerk.

 

Why, in your opinion, would a 5w/30 be acceptable in Winter but a
10w30 be preferable in Summer?
Consider that both are the same viscosity at hot working temperature
before you answer.

Huw

 

Thicker oil viscosity and sheer strength according to the Mobil 1 specs

 

Careful with the name calling Philip.

 

In

Hard to imagine anyone would not know what a circle jerk is.

 

specs


No it doesn't AFAICS. I believe you are mistaken. The viscosity rating
is transparent. Both are the same 30 weight oils [in simple terms]
at operating temperature. The 'W' rating is not relevant to Summer use
or to the engine at any sensible ambient temperature. Both are fine
down to well below freezing point of water in nearly all modern
engines as far as viscosity is concerned. Similarly, both are fine for
use in high ambient temperatures because they have identical [within
the scale limitations] viscosities at engine operating temperature.
What is difficult to understand about this?

Huw

 

Generally, it is preferrable to use the smallest viscosity spread (the
difference between the number before the 'w' and after the 'w') that will do
the job because the smaller the visc. spread, the less VIIs have been added,
and the more shear-stable the oil is. When the oil shears, it can move out
of its original viscosity range, but more importantly, one of the effects of
shear is sludge being deposited inside your engine. So, if it's not cold
enough to mandate a 5w-30, then 10w-30 should be used to avoid the problems
described above. But generally, yes, both will do the job in warm climates,
and if people insist on changing their oil every 3-4K miles, then most of
these problems may be a non-issue altogether.

Cheers,

Pete

 

In

"Car Guy" may be a Canadian. Ever notice how cold climate people
tend to place emphasis on the "winter" viscosity ... as if engines
never warm up?

 

....because the majority of the wear in the engine occurs when it is cold,
and the oil is not warm and moving through the engine as it does when it is
at normal operating temperature..

 

Sometimes, they never do! Further "Since 90% of engine wear occurs as
startup", it is a little important when "startup" is at -10 to -20 F on
MANY mornings.

Dan

 

Purely an old wives tale. The Mobil 1 0w40 is their most stable and
long lasting product. Many 10w/40 oils today are stable for 60,000
miles or more, the only limitation to further use generally being the
level of contamination.

Huw

 

"Philip®" >

Now you come to mention it ;-)

Huw

 

Then why claim that a 10w30 is better in Summer when a 5w30 is equally
good?
There must be a general mental block on this subject!

Huw

 

The path of oil delivery is not affected by temperature. The
delivery time to regions of "boundary lubrication" are most affected.
This would be the piston rings as they are lubricated by oil thrown
from the connecting rod journals, in most cases (some engines have an
oil jet aimed at the cylinder wall, fed by a pressurized oil gallery.
How much time elapses before boundary regions are lubricated after a
cold start?

 

In

Dan..... are you tellin' me that "sometimes" engines never warm up?
How can that be, pray tell? When engines run, they make heat.
Thermostats control coolant temperature. We're not talking about
diesels in cold weather.