0W-40 in 1970 Cadillac Eldorado

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Actually, the 1970 500 has virtually no smog equipment beyond the pcv, which doesnt hurt a thing. 400 HP and 515 ft/lbs with a perfectly smooth 700 rpm idle and 15 mpg is crazy good. I've swapped them into a 84 camero and a 71 chevy truck. Even better is a smogger 500 from 73-75 with closed chamber heads from a 60's 425. 13.5-1 compression with good flow, 450 hp. Cant run pump gas though...


smog laws (not nader...) the compression went from 11-1 to 8-1 and rthe cam was changed drastically. But I digress... HTH, Ben
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Actually, the 1970 500 has virtually no smog equipment beyond the pcv, which doesnt hurt a thing. 400 HP and 515 ft/lbs with a perfectly smooth 700 rpm idle and 15 mpg is crazy good. I've swapped them into a 84 camero and a 71 chevy truck. Even better is a smogger 500 from 73-75 with closed chamber heads from a 60's 425. 13.5-1 compression with good flow, 450 hp. Cant run pump gas though... ================ I am fairly sure it had a smog pump on it, and a bunch of other stuff. My 74 sure did.
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So my decision at the moment is to change to a regular, nothing-special-about-it, 10W-40 motor oil in the Spring. I'll use a K&N oil filter, though I've never found them any better or worse than any other oil filters. Mobil-1 doesn't make the filter for this car anymore.
Any suggestions for a good oil filter for this car while we're at it? Anyone disagree with my ultimate conclusion about oil grade?
Someone suggested 20W-50 for the Summer. Dealership told me that'd be a bit on the thick side. Moving to South Florida later in the year, so is that an even better incentive to go to 20W-50?
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Take a look at the Purolator ONE filter. You won't need 20 w 50 unless you plan on either racing the Eldo or doing LOTS of highway driving. Conventional oil, Texaco Havoline is about as good as it gets. Shell isn't bad. Havoline is dirt cheap in most auto parts stores, Wal Mart etc. You won't find any conventional oil that's better. There are several just as good. Shell, Union etc. The fact is you can get Havoline anywhere.
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only way to really answer is to watch your oil pressure gauge. if it's in spec don't worry about it. Purolator, Wix, Luber-Finer all make good filters. If you want to "drive it forever" check out the Canton Mecca replaceable element filters. Not cheap but supposedly the best full flow filters you can buy. Just use a good quality oil with a decent amount of ZDDP.
nate
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How old is "old" oil? I have an unused/unopened quart bottle of Mobil Drive Clean 10W-30 that I'd like to find a use for. They haven't made Drive Clean in a few years. Generally how long is a bottle of conventional oil good for? I understand synthetic is good for quite a few years.
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One quart isn't going to do for your engine. Use it in a lubricating can for bicycle chains chain saws etc. Never MIX oils in a good engine. Or give it to a friend who has an oil burner.
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Yes I know. The car takes 5 quarts.
But lets say I have some oil from, e.g., 2003 still hanging around in unsealed bottles. (Mobil Drive Clean). Should I recycle it or is it still fresh enough to use in a car that requires that grade (10W-30 in this case)?
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Motorcraft makes a nice 5W-50 full synthetic. Anyone have any thoughts on that for the '70 Eldorado with the 500 CI motor?
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The Derfer wrote:

Winter is going to be over before you reach a decision.
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Most synthetics are good oils. But is is not good to mix type of oils. Stick with whatever you have been using. Don't just switch back and forth because somebody tells you synthetics are good. Pick a lane and stay in it.
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AutoZone has a brand called 'ValueCraft'. What manufacturing differences exist between something like that (the cheapest in their store) and, say, the major brand names? And in another forum I saw someone get really DOWN on the Pennsylvania oils (Quaker State, Pennzoil) as awful. What's the bias there?

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D> AutoZone has a brand called 'ValueCraft'. What manufacturing differences D> exist between something like that (the cheapest in their store) and, D> say, the major brand names? Literal answer I don't know. If the package doesn't tell you, it could be almost anything. Could be old product Shell one can, old product Union oil in the next can. If it doesn't say on the package my bet is that the folks at the AZ store won't know any more than you would. I like to stick with what I KNOW is good.
D> And in another forum I saw someone get really DOWN on the Pennsylvania oils (Quaker State, Pennzoil) as awful. D> What's the bias there?
Sure and I share the bias against paraffin based oils. (Pennsylvania). If you have ever seen engines torn down you would too. They gunk the hell out of engines. Especially I would never use it in a modern high rev engines. They deposit sludge everywhere. Which is why I like the synthetics so well. With an older car like your eldo, where you have been using conventional oil, stick with it, but stick with the majors. Texaco, Union, Shell, Phillips etc. Just be consistent. Avoid the cheap oil unless your motor is shot.
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Do you have an opinion on Mobil Clean 5000 and 7500?

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5000 is a conventional oil. Very good. 7500 is a synthetic, not as good as Mobil 1 but good. Both are older versions of newer oils. Look for the expiration dates on the case they came in.
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Interesting. Mobil Clean 5000 comes in a 10W-40, I think that's what I'd prefer to go with in a 10W-40. I trust the brand well enough.
Last questions, slightly off-topic:
Does anyone recommend a "crank-case cleaner" to wash the gunk out of the engine? The type of fluid that you put into an empty crankcase, run the car for 10-15 minutes and then empty, and refill with oil afterward? I've heard those are mostly kerosene. I'm not sure if that's such a great idea since it may strip away deposits that maintain clearances within acceptable tolerance. At that point, I might have to go with 20W-50 all day every day, for example. Consider, though, that this is an OLD engine with low miles (actually closer to 57,000; I checked the other day). Would a regular diet of a double- does of Techron do just as well?
And what happened to SNAP brand lead substitute? It used to be the cheapest out there, now I have to buy 'Gunk' brand which is almost 2X more expensive. So few places carry a lead substitute on the shelves anymore. Frustrating. I always use 93 Octane.
I've tried Octane Boosters with varying success. This motor was used to 100-104 octane in its younger years. Is there an effective Octane booster that can get the engine a little more responsive these days? Someone suggested aviation fuel but with its explosive qualities, I wonder if plutonium would be just as wise.

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D> Interesting. Mobil Clean 5000 comes in a 10W-40, I D> think that's what I'd prefer to go with in a 10W-40. D> I trust the brand well enough. I am not sure they are still making it. But it was known to be a very good oil.
D> Last questions, slightly off-topic: D> Does anyone recommend a "crank-case cleaner" to D> wash the gunk out of the engine? The type of fluid that D> you put into an empty crankcase, run the car for 10-15 D> minutes and then empty, and refill with oil afterward? Old mechanic's trick is to run automatic transmission fluid. I am not sure I really reccomend it. I have heard of engines giving up the ghost when cleaned like that. ATF is highly detergent. The process is to drain the oil and put on a CHEAP new filter. Fill with ATF. Drain replace with clean oil and a new filter. It may clean out TOO MUCH of the gunk. The engine may be depending on that gunk to function.
D> I've heard those are mostly kerosene. I'm not sure if that's D> such a great idea since it may strip away deposits D> that maintain clearances within acceptable tolerance. ATF is highly detergent. It cleans everything. On an old engine it may have all kinds of problems. Better to either rebuild the engine or just use good oil and stick it out.
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On Sat, 7 Mar 2009 17:04:48 -0800 (PST), The Derfer

MobilClean is designed to be an extended change motor oil. Do you really plan to put enough miles on the engine for this to be an issue? On my '59 I change the oil in the spring and again in the fall and find that this is often less than 1500 miles on the oil.

Have you ever heard the saying "If it ain't broke, don't fix it"?
Steve B.
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I suppose a bottle of Techron every few months will be just as good.
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One of the problems with doing that to an OLD engine is that often they stop running and a rebuild becomes mandatory. The advice, "If it ain't broke don't fix it" is the best you'll ever get. Pouring lots of crap (chemicals) in an engine makes the companies that make the crap very happy, and can also serve to make all the companies that sell rebuild parts for engines VERY happy as well. One of my pet peeves is shadetree mechanic engine rebuilds. What you slap new rings and gaskets and hope like hell it runs when it is back together. If you are going to rebuild an engine, take it completely out of the vehicle. Strip it to the bare block. Send to to somebody reputable to be magnafluxed to check for any small cracks. Then "tank it" to clean all the gunk off its innards. They you have to check all of your tolerances for your crank journals and the cam. Most likely you'll need a new cam. New lifters etc... Redo the heads. Big job. Not all rebuilt "crate engines" are very good. Be sure of the source. I was in the parts business for a time. LOTS of bad crate motors especially on the big block engines. Like a 500 CID. Yes, a GOOD engine is going to cost you up the ass, but a cheap one costs even more.
Best to leave sleeping dogs lie. There are no miracles in a can. Just keep on with good oil and decent filters and stop playing games. Synthetic oil is good in a new engine. Even a new OLD engine. But screwing around with an old, old engine changing this is a high risk thing. It keeps coming back to; "If it ain't broke, don't fix it."
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