0W-40 in 1970 Cadillac Eldorado

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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. ======== Good advice.
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You might get away with it, but I would never do it. The only engines the call for 0w40 have micro polished crank journals. Using 0w40 could cause rapid wear, and it would be a crying shame to wipe the bearings on such a rare engine. The Rotella is *great* stuff but would probably show no benefit on such a low mileage engine. I use it exclusively on both my hi mileage vehicles. HTH Ben
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So then you'd recommend a conventional 10W-40?
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wrote:

I suggested Havoline 5 w 40 in the winter, cheaper and does as good a job with your engine is oil costing 10 times as much. This all depends on how much you drive the car and many other factors. Is it garaged? With an engine of that vintage you just won't get anything out of synthetics that make it worthwhile. Just stay away from Pennsylvania oils. Anything paraphin based. A good grade major oil company oil, Texaco, Shell, Union 76, Phillips are ALL good. You can get that stuff dirt cheap in most parts store or Wal Mart. Just NEVER buy a house brand. Any MAJOR oil company's good grade oils. Frankly a 10 weight in winter and 30 weight in summer is even better.
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The Rotella isn't like a conventional 10W-40... it's made with petroleum base stock, but it has a lot more ZDDP in it than a modern conventional oil does. This is a big deal for the cam arrangements in many older engines. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Scott Dorsey wrote:

Depends on which Rotella you're talking about. Regular Rotella T is conventional base stock. Rotella T Synthetic is Shell's XHVI (extreme high viscosity index) base stock. Its a "Group III+" base stock, refined from hydrocracker bottom slack wax and severely hydroprocessed, dewaxed, and further refined. Its wonderful stuff, and performs almost identically to Polyalphaolefin (Group IV) synthetics. In fact it carries additives a little BETTER than Group IV base stocks. Often PAO synthetics like Mobil 1 and others will add some conventional group II/III stock to the mix to carry additives that the PAO won't.

It appears that scare may have been greatly overblown. Certainly once a cam has been initially broken in, its need for high doses of ZDDP is about nil. Especially with factory valve springs that don't have a seat pressure of more than 300 lb or so. The latest diesel oils (Rotella- both flavors, Delvac and Delvac 1, Valvoline Premium Blue, Delo 400, etc.) are also reducing their zinc content, but at a slower rate than gasoline oils. The latest Rotellas are now gasoline SM and diesel CJ rated, which means that the zinc is coming way down.
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Yes I would. And 20/50 for the summer. HTH, Ben
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ben91932 wrote:

Why would you EVER run a 20w50 in anything that doesn't consume oil like a mosquito fogger?
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Because that is what the book recommends for the climate I live in? (several old VWs and a Porsche 944)
nate
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N8N wrote:

OK, air-coolers are a different story. But 20w50 in anything water-cooled in the US is just... odd. Maybe something that is so worn-out it can't hold oil pressure with anything else...
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I am talking about water cooled engines. It's in the book. normal summer temperature ranges around here call for either xW40 or xW50 based on the chart in the owner's manual. xW30 is for winter only.
nate
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We had a 1983 Mercury Cougar. We loved the car, but it needed regular repairs and died at 99,960. (Yes, as a matter of fact, I *did* contemplate renting a Clydesdale to pull it the other 40 miles . . . but we were packing for grad school, and I just got rid of it.)
Anyway, it called for 20w50 in its factory handbook. Then again, it called for three different oils throughout the year in some climates. I think I got away with only two here in Las Vegas.
hawk
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