Oil for very long OCI in 89 Cadillac?

[AstroVic]

This is your chance to help me pick an oil to abuse (well, sorta). Yippee!!

Well, my dad handed down his 1989 Cadillac Sedan Deville with the 4.5L V8. He owned the car since new and generally took very good care of it. He passed it down to me when my Crown Vic was totalled about three months ago.

The Caddy's currently going through an Auto-RX treatment (rinse phase). It has a relatively small oil leak (a couple of drops overnight), but nothing to cause any significant concern. It doesn't seem to burn any oil, but I haven't really had it long enough to be sure. Everything is mechanically sound on the car - it doesn't smoke, misfire, run rich, run lean, overheat, etc. It averages about 21mpg on the highway.

I drive the car about 360 miles per week, four days of approximately 45 miles each way from one side of Houston to the other for school. I usually cruise at 65 to 70mph. Most of the driving is done during lighter traffic periods, so I don't really hit a whole lot of stop-n-go conditions. (I go to school in the evenings.)

I plan on doing an extra-extended OCI just for kicks and grins. (I usually do 5,000 and under, so keep that in mind!) I think the Caddy is up to the challenge.

I plan on using a Wix oil filter, but I'm undecided on the oil.

Should I go with something like Pennzoil (regular variety or High Mileage) 5W30 and push it to a 10,000 to 12,000 mile OCI? Or should I go with Rotella 5W40 synthetic and see how far I can sanely push it? (I'm fearful of developing the small leak into something bigger, so I'm kinda concerned about using the synthetic in this car.)

Or should I try something different? TropArtic, SuperTech, Valvoline...?

Give me your thoughts. Like I said, I plan on pushing the oil to a hypothetical extreme mileage, but not so far that I completely destroy this car. (I definitely don't want to KILL the car!)

[ June 20, 2006, 11:41 PM: Message edited by: AstroVic ]

 

[TheTanSedan]

As detailed in other posts, on the acquisition of several used cars:

1] Molasoak
2] MOPAR Combustion Chamber Cleaner
3] ARX with diesel-rated oil, both phases
4] RED LINE, with LUBE CONTROL LC-20 and either a BALDWIN B2-HPG or DONALDSON P169071 filter

OCI of up to 10,000 miles is the parameter, with changes past seven thousand to nine thousand in practice.

 

[johnsmith]

Did you ask your father what kind of oil/OCI he used, how it ran, quirks, etc.? You do need a "baseline" to compare with after all.

Hows about spark plugs, fuel filter, etc.? If you feel the need to tinker around with something, I would probably start there first. If the engine had high miles and ran great, the oil brand/weight/type would be the last thing I would touch, personally. How many miles on the car?

 

[AstroVic]

The car has brand spanking new spark plugs (AC Delco), fuel filter (Wix), transmission fluid & filter (Wix), coolant, PCV (MicroGard), and air filter (AC Delco).

Throughout the life of the car, my dad typically had the oil changed at Walmart every 4,000 miles or so. His last two oil changes went one year OCIs with about 3,700 miles each time.

Guess I should add that the car currently has 141,500 miles on it.

 

[johnsmith]

Looks like someone's been busy!

So are you saying can we assume it's been getting a diet of something like bulk dino Super Tech, Pennzoil, etc. for most of it's life? What kinds of conditions were the car driven under? Can you tell us what viscosity (or viscosities) might have been used? Has the engine ever had any major work done on it? I would say it's important to find out if the car burns any oil or not too.

Even if you had access to an exhaustive history of the car, I would still run it through at least 1 or 2 plain Jane intervals "just because". (e.g. 4/5k OCIs with Pennzoil dino or something...) Obviously though, we're two different people, but we do need a few more details in order to give a good recommendation.

[If I was in your spot and couldn't/didn't know a **** thing about the car, and was determined to do a 10,000 mile OCI with your driving habits in your climate for whatever reason, I might try something like a good 5w40 or 10w40 (*gasp* Maybe even a 15w40? How hot is the Texas heat where you're at? No, no that's crazy talk, maybe I would just "mix a little in"...] with a filter change halfway through (and check oil level often)].

 

[AstroVic]

Yes, you can assume it's had whatever bulk dino oil the lube place had on hand that day - almost certainly Super Tech or Pennzoil. (This is about the only area where I disagree with my dad's car maintenance philosophy!)

The car has been maintained almost exclusively - apart from oil changes - by a Cadillac master mechanic who does work on the side outside the dealership. There have been no major repairs or rebuilds of anything - just your typical minor wear and tear items here and there. It even has all original paint with not a single door ding anywhere to be found. The car sat in a garage and was covered under a car cover any time it was left outside for more than a few hours (seriously!).

Most of the driving in its life was short trips (about 3 miles each way) to the shuttle bus location. There were MANY very long road trips sprinkled in there (cross country and throughout Texas), which probably account for about 75,000 of the miles on the odometer.

Houston generally gets no colder than 40 degrees in the winter, with a few spurts in the 30s. In the summer its usually 95+ degrees with very high humidity (sometimes 100%!).

 

[LargeCarMan]

Try Castrol High Mileage Group III synthetic oil and analysis it at 7K...that's a conservative number "or" Valvoline Maxlife Group III synthetic with the same set-up.

 

[AstroVic]

I should probably point out that my main objectives for doing this are:

A) I'm extremely busy with law school and I don't really want to change the oil as often as I have in the past due to the fact that I basically have zero free time these days (except to hang out on BITOG from time to time!).

-- and --

B) I'm curious to see how well an oil will perform if it's pushed to the outer limits. Again, I don't want to push it so far that I ruin an otherwise fine car. I just want to see what'll happen if I break out of my short-OCI mentality.

Even doing something like taking Mobil EP all the way out to 15,000 miles would be interesting. I'm still a little nervous about the synthetic thing, though.

 

[Rand]

I'd stay away from syn.
My '91 4.9 was leaking like a sieve after 3000 miles
of m1 truck and suv.

It has slowed down now to about a quart every 2000 miles.

Hopefully the free from bitog castrol HM and M1 filter will slow it even more. (Thanks Tony)

 

[m2200b]

When you find you have zero time to even do an oil change or see friends - you probably are under stress and ought to deal with that not the car.

 

[addyguy]

I know there is a concern about leaks, but if you get that under control, and want to push an OCI to the extreme, why not try seeing just how far you can go with one of the Amsoil products?

On their top-line oil, they say you can go 35k miles between changes, and thats probably if you don't need any top-ups. But if you need to do periodic top-ups, and you do 6 month filter changes, you could probably go almost indefinetly on one change of oil.

Maybe do an UOA once a year to see how the oil is holding up, but I don't see why if you are replenishing the oil every 2 months or so (as an example), you couldn't keep an oil going basically forever. I don't think you would do any damage to the engine doing this, and the rest of the car ould probably have problems loooong before the engine did!

 

[AstroVic]

addyguy,

Thanks for the comment. (And I agree with what you're saying, by the way.)

The only thing is: I don't like Amsoil.

(Sorry, Amsoil reps! It's nothing against you guys!)

Perhaps the same could be said for Mobil EP? Assuming there was a quart added here and there, if that even becomes necessary.

 

[KW]

Rotella T 5W40 with annual OCI's and a fiter change every six months should work for you.

But seeing that you drive over 18K a year it might be better to have a sample checked after 10K to see how it is doing.

 

[milwaukee]

How about using plain oil dino with lube control?

I always wanted to try lc20 and this seems like a great test.

 

[Gary Allan]

I'll agree with KW ...but skip the filter change. Both will break ground that I haven't yet ...but I believe that it will work out fine.

 

[sprintman]

OCI's here are mainly 15,000kms with some 20,000kms. Dino oil. You shouldn't have a problem with the rec's above.

 

[reyjay1]

I was thinking a nice hd 5w-40 as well but a little more upscale , like a Delvac 1, or just go redline for the 18K.

 

[BUBBA0420]

AstroVic: You have a nice well maintained
car that cost you nothing. Why do you want to
abuse it ???? You don't have time to change the oil ??? MAKE TIME !!! It only takes 30 min
to do it yourself

 

[TomJones76]

In your climate, I'd feel comfortable running 15W40 in that thing. Big TBN, low price...

 

[Black Thunder]

why not even a 10w30 HDEO if you can find it.


around here Rotella 10w30 can be had for under 9 bucks a gallon, with a robust add-pack you could push the oci a bit