Cadillac: 0W-40 in 1970 Cadillac Eldorado

On Feb 16, 9:34*am, The Derfer <com> wrote: 

All I can say is try it and find out. I did try the 0W40 in my 944
once and found that it thinned out at high engine temps enough to
noticeably drop the oil pressure as indicated on the gauge. 5W40 syn
would not do this. If you have an oil pressure gauge try it for a bit
and see what happens. Be aware that if you switch from dino squeezins
to syn you may notice an increase in seal/gasket leaks, even though
the oil mfgrs. have done a lot to mitigate this from the 1st gen of
synthetics.

nate

An enviable car, as long as gas doesn't go back up to $4!

I'd say that:
* Switching to a synthetic or a high-detergent (fleet; diesel) oil on
a non overhauled "survivor" engine that old is asking for trouble.
* It's coming up on its 40th birthday and counting, so what you've
been doing plainly works.
* Although large and powerful it is not a highly stressed engine.
* There was a fair bit of sophistication in motor oil by 1970; most of
the changes since then have been responses to problems that evolved
since then (hotter-running, higher-revving engines, pollution
concerns, etc.)
* Looking to advanced and/or lighter motor oils to improve the fuel
economy of a 1970 Eldorado is like firing the aft guns to improve the
fuel economy of a battleship.
* Any car of that age is likely to dirty its oil faster than a modern
car in good condition.

I might go with a "high mileage" conventional (dinosaur; non-
synthetic) 5W30 if you are concerned about cold starts for what little
driving you do in winter, 10W40 like you've been using in summer,
changed every 3000 miles with a quality new filter. And many more
happy years of cruising!

One man's opinions, worth what you paid if your ISP is inexpensive,
--Joe

"The Derfer" <com> wrote in message
news:googlegroups.com... 


It is not wise to switch tyhpes of oil. Synthetic is great if you never
use regular oil. If you have ued regular oil, stick with it. With that
engine, I'd suggest you use an arctic grade oil unless you are going to
drive lots of highway mines. Then a goof 5 w30. Texaco Havoline is good.
Shell has gone good oils as does Castrol. AVOID standard Pennzoil or Quaker
state in that engine. There are some other good oils out there. If you ever
do a complete rebuild of the motor, stick with a good Synthetic like Mobil
1.
 

Not at this point when you have used conventional oils. Only if you
completely tear down the motor, at least hone the cylinder walls and give
the block and all parts a good bath. I know there will be folks who will
disagree with me on this point, it has been my experience that convention
oil and synthetics don't mix. Pick one and stick with it. There are good and
bad in both. The whole issue of multiple viscosity oil is largely a myth.
There are laws of fluids. All fluids are thicker when cold and thinner when
hot. All this multiple viscosity crap does is plays with the clock. How much
time it takes to get thick and thin.

< I ask because the only cars which are ever 


The Mobil 1 is GREAT oil. You won't blow up your motor using it or
anything, but the residue conventional oil will act like a contaminant in
it. You won't get the performance you would have in a new engine. I can't
recommend any oil higher than Mobil 1. Castrol Edge is pretty spectacular as
well.

Interestingly, the manual for this car (which is close to 40 years
old)
specifies a rather wide variety of grades for this car. I have to
believe
they were vastly different in 1970 so I pay it no mind.

Everyone always said "10W-40" as the default response for that car.
Can 0W-40 be anything (significantly) different other than it's
viscosity
at cold temps? I think of 10W-40 and 10W-30 (which I've used
occasionally
in the past as well) as identical at cold temperatures.
Speaking of temperature, about how hot DOES this kid of car run?
Everyone
talks about cars "running hot" these days. Is this relative? Did
cars
"run hot" back then? This is a 500 CI motor after all. I just don't
know.

I've used 15W-50 Mobil-1 synthetic and other grades of conventional
oil
(10W-30 up to 20W-50) before. None produced any ill effects that I
can
report. The engine does leak oil to a degree and none of those oils
made
it better (or worse). My real question is would 0W-40 make for easier
starts
in the cold? I want to make the engine last (never have to rebuild
or replace)
so synthetic is an option I'm thinking of returning to, and perhaps
0W-40
is the right grade for every situation. But if people have other
ideas, I'm
always listening.

I have found the posts so far very imformative: a big thanks to N8N,
KRP
and Ad absurdum per aspera.

-The Derfer

= = = = = = = = = = = = = = = = = = == = = = = = = = = = = = = = = =
= =


On Feb 16, 11:04*am, "KRP" <net> wrote: 

"The Derfer" <com> wrote in message
news:googlegroups.com...
Interestingly, the manual for this car (which is close to 40 years
old)
specifies a rather wide variety of grades for this car. I have to
believe
they were vastly different in 1970 so I pay it no mind.

Everyone always said "10W-40" as the default response for that car.
Can 0W-40 be anything (significantly) different other than it's
viscosity
at cold temps? I think of 10W-40 and 10W-30 (which I've used
occasionally
in the past as well) as identical at cold temperatures.
Speaking of temperature, about how hot DOES this kid of car run?
Everyone
talks about cars "running hot" these days. Is this relative? Did
cars
"run hot" back then? This is a 500 CI motor after all. I just don't
know.

I've used 15W-50 Mobil-1 synthetic and other grades of conventional
oil
(10W-30 up to 20W-50) before. None produced any ill effects that I
can
report. The engine does leak oil to a degree and none of those oils
made
it better (or worse). My real question is would 0W-40 make for easier
starts
in the cold? I want to make the engine last (never have to rebuild
or replace)
so synthetic is an option I'm thinking of returning to, and perhaps
0W-40
is the right grade for every situation. But if people have other
ideas, I'm
always listening.

I have found the posts so far very imformative: a big thanks to N8N,
KRP
and Ad absurdum per aspera.

Having had one of those glorious beasts Eldorado with the 500. . . I can say
they are particularly delicate motors. It was not one of GM's better
offerings. Neither was the pain on the Eldos, particularly the metallic. I
think the engine would do okay today if you had a new one and stuck with oil
like Castrol Edge. For some INSANE reason, it seemed like many people used
Pennzoil and Quaker State in those engines. By the time they had 50,000
miles they were full of sludge. Cylinder walls horribly varnished and
scored. They were blowing oil like mad by 65,000 miles. Seems like people
with other GM vehicles were not as prone to use that crappy Pennsylvania
oil. Don't switch. Use a major brand conventional oil. Like I said Texaco
and Shell have really good, inexpensive oils as does Union 76 and Phillips.
Stay away from the off brands and chain store oils. (K-Mart - Wal Mart etc)
House brands. Castrol makes really good oils too.

The 500 isn't a bad engine if you care for it properly. Like I said, if you
got a new 500 it probably would hold up well. GM engines of 1970 generally
weren't the best. That was a dark period for American cars in general.The
bad American cars of the 70's is why you see so many Japanese cars today on
our roads. Detroit was largely building "shit." The engines had all that
emissions crap on them that really didn't work well and burned valves etc.
Rube Goldberg devises thought up by Ralph Nader types who had NO idea what
makes an automobile run. That is another reason Japan & Company got 55% of
the American car market. Japanese cars didn't have to have all that crap
sucking the life out of their motors.

 

Lots of things have changed with engine oil over the years but but the
weight still means what it meant. Your chart in the manual is still
good. 

It takes more viscosity modifiers in the oil to get the larger spread.
As the oil ages the viscosity can drift off. My understanding is this
isn't as big of an issue with synthetics as it is with regular oil
 

Stock thermostat was 195. The temp goes up to 220 ~ 230 on a hot
summer day idling in traffic.
 
On newer cars the computer doesn't turn on the fan until the temp gets
higher than what you would have seen in the old days. A new car may
not even turn on the fan until 220 degrees. Your Cadi's cooling
system is getting is working as hard as it can and loosing ground
around this temp.
 

Yes 0W-40 can make it easier to start in the cold. What kind of cold
are you talking about? Is this your daily driver? Personally if I
wanted the engine to last forever I wouldn't be starting it at all in
temps where I was worried about oil flow. Will the oil make any
difference long term? Well I guess you pick your pony and take your
chances on that one. I would pick one oil and stick with it though
and quit doing this multiple products and multiple weights stuff.

Honestly at this point in the cars life what you do today isn't nearly
as important as what has been done to it over the last 40 years. On
the plus side the 472/500 was, IMHO, one of the best engines to ever
come out of General Motors. I have had several that were poorly
maintained with a gazillion miles on them and you just can't kill
them. Now the CV joints... that's another matter alltogether and I
wouldn't wish them on my worst enemy!

Steve B.

On Feb 16, 9:34*am, The Derfer <com> wrote: 

How many miles and years on the engine. If it's a long time I would
just switch to 5w30 non-synthetic. Running synthetic in an old engine
could cause it to start leaking. For those cold northeast mornings
just install a block heater and solve any cold start worries.

On Feb 17, 8:45*pm, "John S." <com> wrote: 

Second the block heater suggestion....better yet, one in each bank.