Oil For Rarely Used Cars???

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Jul 11, 2003
Besides our daily drivers we have a few old cars for fun ('65 Caddy, '67 Jaguar and '72 Volvo). All are in excellent mechanical condition including engines which have been rebuilt within the past 10,000 miles of use.

None of these vehicles sees more than 2,500 miles of driving per year. They spend most of their time tucked away in our garage here in mild California weather.

Although low mileage, they do not see a huge number of start/stop cycles.

Currently I change the oil and filter annually and have been using just about any major brand oil on sale. My thought is that with the low usage it probably does not matter very much.

One puzzle is the oil weight question. Is it better to run a thinner oil like 5W-30 in order to get the fastest pump up, or is it better to put in something hefty like a diesel 15W-40 oil in hopes that it will stay stuck to the internal longer during the long drain down periods?

Your expert advice would be appreciated.

I think more important than viscosity is selecting an oil with the right additives...in my opinion, one high in zinc/phosphorus and molybdenum to provide a layer of protection before the fluid film can be pumped up from the sump.

Why I say this is because after sitting for awhile, no matter if you're running 0w-20 or 20w-50, the fluid film is gonna drain back down into the pan, making the engine count on the boundary lubrication properties of the oil to protect it.

Pennzoil Long-Life 15w-40 meets this spec, but it also will take longer to pump up than a lighter viscosity oil, but you do mention they are kept in a garage in a "mild" climate, so I believe the Long-Life will "pump-up" plenty fast enough.

Do you want to go to a synthetic oil?

Without going to a synthetic (Light viscosity and high doses of moly/zddp, such as Redline), I believe the best bet is Long-Life 15w-40 in these 1965-72 cars that can easily handle the viscosity.

If engines are not using too much oil, and you don't mind spending a littlle more than "whatever is on sale", a good synthetic could work very well since the engines have been rebuilt and all seals should be good.

Just my two cents...

[ January 27, 2004, 04:48 PM: Message edited by: Jelly ]
That's the age old question and there is no age-old answer. But looking at it logically 1. All oils are thicker cold than hot. 2. the colder you get the closer a 5W-30,10W-30, and 10W-40 get to each other. 3. At say 70F the 5W-30 is 150 centistokes and 10W-40 is 250 centistokes compared to an operating viscosityof about 11 centistokes for 30 wt. and 14.5 centistokes for the 40 wt. (much thinner than the oils at 70 F.)

My guess is that either is "thick" enough to handle the startup chores of oil that is just sitting there on the bearing. But I still think the most important aspect is the flow (in colder climates). In Cali the flow isn't critical. Since you are in Cali-I think the choice would be for you either a 10W-30 or a 10W-40. The 10W-30 will hold up better and the 10W-40 might protect the bearings just a Tad better-especially if the vehicles are driven hard. Your choice
Probably doesn't matter a lot (IMHO)
If the cars are infrequently run, I'd lean toward one of the diesel 15W-40 oils (most of which are SL for gas engines, too). The additive packages are generally good for corrosion resistance (among other things) which I think is important if the cars sit alot. I've had good luck with both Valvoline Premium Blue and Chevron Delo. Pennzoil Long Life has a number of fans on this board as well.

What Volvo do you have - 1800, 142, 164?
Let me make an uneducated stab at this.

Seems to me that one of the problems you have is internal rusting of your engine. Both on the oil side and the coolant side. So besides the afor mentioned barrier additives to help with your really dry start condition. I'd look for an oil that has excellent anti-rust proproperties.

I'm not real sure what additives impart anti-rust properties. Group I oils and antimony come to mind but thats just speculation. I am sure a true expert will appear and let us know.

Of course in a world not ruled by economic limits a aux. electric oil pump would be solve your problems. Then you could circulate oil occasionally and especially just before start up. Sounds expensive doesn't it!

Maybe a pre-oiler is in order. Though I doubt the pre-oiler systems I've seen will hold pressure for more than a few days.
To sum up:
-The vehicles are old tech, and less demanding on oils.
-The engines are "tight," and therefore don't excessively pollute their oil like a beater would.
-Your mileage is low, less than 2,500 mi/yr.
-Modest amount of cold starts and thermal cycles.
-The climate you drive in is relatively warm.

These oils are enjoying a life equivalent to a trust fund 30 yr old living on a Cancun beach. Quite the EASY life. Personally, I'd buy the least expensive name brand "SL" oil I could find, like Pennzoil for 69 cents after rebate. An old 1973 Peterson's general repair guide I have lists 10w-30 and 10w-40 as appropriate weights for all temps above 0 degrees F -- I would think the latter might be more appropriate for the 100+ degree summer months. I'd make sure to check the Jaguar manual on proper weight.
Thanks for the many interesting and useful posts. I can pick up Chevron Delo 15W-40 by the case at our local Costco and if fact have a case on hand for use in the old Massey diesel tractor we have. It sounds like that oil will probably do just fine in the older cars as well. I suspect that it is very similar to the Pennzoil Long Life, though I do not know so for certain. Those big gallon bottles are much more convenient than 1 quart bottles.

Synthetic seems like way overkill to me for the Trust Fund life these old girls are enjoying. Don't want to spoil 'em too much

Thanks again!
Id say to use a schaeffers oil, or else get some of the #132 (I believe) oil additive. I say this because any good oil ought to have a nice additive package that will provide some barrer protection, detergents, dispersants, and so on. The schaeffers contail Antimony, which is a powerful anticorreosive. Couple that with a nice extra shot of Moly, and your in business. Its thick stuff, so depending on your oils viscosity, dont add much, or suck up the shipping cost and buy schaeffers.
Thats what Ill be doing on my truck soon, becuase it sits for over a week at a time and doesnt accrue many miles. I have been adding the 132, but I think just getting schaeffers blend is the best bet for my buck since its high quality and probably about the same cost as m1.

Ok, I`ll interject something here, and you can take it for what it is worth!

I manage a large car collection with everything from Ferarri`s to Old Corvettes! We are in the process of changing them all over to the 15W-40 Amsoil diesel Marine! I seriously doubt if any of these cars will ever have there oil changed again!

They all get driven at least 25 miles a month, and if not they are warmed up to operating temp!

We went this route as it was just too much trouble keeping up with the oil changes! there are ten cars in the collection!
I have the same concern. My 70 Camaro gets driven less than 1500 miles per year but when I do drive it the engine always reaches full operating temp for awhile. Drives are always over 15 miles but sometimes in the winter it will sit for weeks without starting. I've never had the oil tested but it 'looks' very clean when I change it. I usually go a year or more between changes.
For 21 years I've owned a 71 Cutlass stored winters. I just rebuilt the engine after 170K... not because of any lubrication issues, but the seals dried out and was leaking oil. The engine was very healthy. I never fussed much with this engine. I simply tried to start it up at least once during the winter to keep the parts wet with lubrication.
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