Recommended oil viscosity

Oh, I'm sure if the engine engineers had the sole and final say as to what
oil were specced, then going on the manufacturer's recommendation would be
a sound policy. But there are all kinds of other spurious votes on the
matter, and usually the engine engineers' recommendation is not the one
that wins.

 

That's because while it sounds commonsensical, and probably appears in
magazines like Popular Mechanics, it's not correct. The evidence is right
in the factory service manuals.

 

I still believe that the engines that are sludging up are mainly due to lack
of maintenance, I may have seen 4 engines get replaced at the dealership,
and out of those 4, I bet 2 were not a regular cust of ours unable to prove
oil changes.
The 2.7 engine that is well maintained will last 150K easy!! I own one
and will buy another vehicle with the same engine.

Speaking of Turbos, My 85 Chrysler Lazer 2.2 turbo went 198k before I sold
it to my sister and I bet she put another 60k on it before she sold it. yes
a few head gaskets were replaced but neve the turbo.. A little Maintenance
goes a long way.... including the 2.7


and I'm going to get hammered by

 

I think we did go thru this once. Working from memory here (risky!!)
but I was thinking we compared some old and new specs, and there were
some piston clearances that had generally tightened up over the years -
enabled by tighter tolerances.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

I credit it with cleaning out and quieting the lifters after I had
stupidly changed over to synthetic oil at 180k (switched back to regular
oil after the clatter started within a week after switching to synth,
then started the MMO). I'll never know if it made a difference or not
in it staying running so good for so long.

 

Hard for me to say. I used to be suspicious of the failures too -
thinking that people weren't changing the oil. But I have since
followed some regulars on DI.net who were doing good maintenance and
their engines failed.

Around '00 or '01, DC did some changes to the 2.7 definitely intended to
fix such problems. There must be something to it.

I did have to replace the heads once on that Subaru (due to blowing the
turbo coolent discharge hose a couple of times before I finally realized
that that hose *had* to be silicone and not generic heater hose (it was
like steam coming out of the turbo unit).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Hard for me to say. I used to be suspicious of the failures too -
thinking that people weren't changing the oil. But I have since
followed some regulars on DI.net who were doing good maintenance and
their engines failed.

Around '00 or '01, DC did some changes to the 2.7 definitely intended to
fix such problems. There must be something to it.

I did have to replace the heads once on that Subaru (due to blowing the
turbo coolent discharge hose a couple of times before I finally realized
that that hose *had* to be silicone and not generic heater hose (it was
like steam coming out of the turbo unit).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Looks like you be right:
http://groups-beta.google.com/group...l+author:Putney&rnum=1&hl=en#4fca3fce172ac05b

posts 85 thru 89

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

I'm pretty sure that CAFE is the driver for the viscosity change, but so
what? Detroit almost never changes anything without some incentive.
Without CAFE, why would they change oil viscosity? It costs them money
to update documentation, change the oil caps printing, etc. If they
don't have a reason to change something like this, they won't.

Matt

 

I'm pretty sure that CAFE is the driver for the viscosity change, but so
what? Detroit almost never changes anything without some incentive.
Without CAFE, why would they change oil viscosity? It costs them money
to update documentation, change the oil caps printing, etc. If they
don't have a reason to change something like this, they won't.

Matt

 

I question that it really matters in a multiweight oil anyway. Years ago I
was told by a mechanic who went to an oil company symposium that
the multiweight oils have the multiweight grades because of special
molecules
the oil companies put in the oil. Over time, dirt interferes with how these
work, and the multigrade turns into a single-grade in the engine, usually
well before the oil change.

Ted

 

I wasn't making a big deal that it was. You are forgetting that my
*only* point was that, in response to criticism that I would dare
recommend that someone go outside of the mfgr.'s recommendations,
knowing that the recommendations are skewed thinner for totaly
non-technical reasons, then one should feel comfortable going outside of
the sacred manufacturer's recommendation to what is technically a better
answer. All you've done is made my case.

And my case is made.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

05 T&C is 5w20. Read your owners manual, it's in there.

 

FYI. I have a 05 T&C limited with the 3.8 motor. The city mileage is
horrible. Nowhere near the EPA rating of 19mpg. We get about 13mpg or so.
Highway mileage is right on the epa rating of 24mpg. Otherwise, I like the
car a lot.

 

Matt - there is a lot of difference between a 1975 and a 2000 car that
should make the 2000 last a lot longer than the 1975. The lower oil
viscosity is NOT responsible for the longer engine life.
Besides that, Mobil 1 3W30 and the 5W30 "swampjuice" the typical lube
shop puts in the crankcase are entirely different lubricants. Mobil 1,
changed often enough? - I'd run 5w30. Lube-Shop Penzoil??? Not on your
life!! 240K is about normal for my vehicles - and I generally run
10W40 Castrol GTX in the winter, and 20W50 Castrol GTX in the
summer.Both of my last Aerostar 3.os and my 88 NewYorker 3.0 went over
the 240K with no oil consumption and no bearing problems. Typical 3.0
Mitsu, the NY went through a few sets of cyl heads due to valve guide
problems.

I'm running 10W40 Havoline year round in both my 3.8 Pontiac and 2.5
Merc.

 

Most manufacturers will void the car's warranty if they find you ran 10W40.
(I should add, not only will, but 'have', many times, when it was
discovered at the dealership in troubleshooting an engine problem.)

Simple rule of thumb, if the manufacturer doesn't recommend it in the owners
manual (and none of them do recommend 10W40) then think twice about using
it. Automotive manufacturers have tested the engines under all weather
conditions and will only recommend those products which are best for both
you and them.

READ YOUR OWNERS MANUAL. There's a reason why 10W40 is not listed.

 

I never claimed that the lower viscosity is responsible for the longer
life. However, I also don't think that lower viscosity shortens engine
life! That was the claim and I simply have seen no data to suggest that
this is the case.

Matt

 

I never claimed that the lower viscosity is responsible for the longer

The simplest method to verify its use, is to look in the owners manual and
see if Chrysler recommends its use. If not, they could (and would) use that
against you in an oil-related engine failure (which in the past seems to
have been stretched to include considerable problems (like excessive flash &
jumped timing belts.) I know for a fact that Ford & GM do NOT recommend it
(or at least they used to, not recommend it.)

I pulled this off the web some time ago, don't remember where exactly.
"Multi viscosity oils work like this: Polymers are added to a light base
(5W, 10W, 20W), which prevent the oil from thinning as much as it warms up.
At cold temperatures the polymers are coiled up and allow the oil to flow as
their low numbers indicate. As the oil warms up the polymers begin to unwind
into long chains that prevent the oil from thinning as much as it normally
would. The result is that at 100 degrees C the oil has thinned only as much
as the higher viscosity number indicates. Another way of looking at
multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin
more than a 50 weight would when hot."

Ok, so a 10W-40 is really a 10W oil with polymers used to keep it from
thinning at higher temperatures. Then the problem with using 10w-40 is that
the polymers used to prevent the oil from thinning at higher temperatures,
can shear and burn forming deposits that can cause ring sticking and other
problems. (This is especially true of diesels, but still true of gasoline
engines as well.) Anyway, this become pronounced in 10w-40 as the base oil
(10w in case) will require a lot of polymers to achieve the range desired.
The wide viscosity range oils, in general, (10W-40 and 5W-30 ) are more
prone to viscosity and thermal breakdown due to the high polymer content
(and should be avoided.)

You could always check it out for yourself by calling your local Chrysler
service manager and ask him if they recommend its use. Don't be surprised if
he tells you it will void your warrantee however.

Personally I use Mobile 1 and run it on an extended, extended service.
Change the filter every 3k and top off.

 

So where do *you* draw the line - how thin is too thin? Without any
data you have no basis to make a decision at all, so keep going thinner
and thinner - after all - you've seen no data that lower viscosity
shortens engine life. (I know - you go by the mfgrs. recommendation.)

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Dennis wrote:

I have a "dumb question": What is "flash" in the context of this discussion?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')