Scenario: a 454 w/ 75k miles, weaned on Penzoil since new.....Typical 454 w/ about a quart use per 1k miles (never seen it burn, never seen it leak - where the heck does it go?!....) All original innards and never any major problems...(Confession: I also add about a pint of Marvel Mystery Oil to gas tank every other fill-up.....Don't ask me to defend the practice...it's just something I do to all my fossil-fueled toys....)

Question: Are there any potential benefits to switching to pure synthetics (Mobil-1)? I've heard it adds a little to cooler running, yada yada.......And is the switch to synthetics that simple, as in fluid & filter change, or is there some ritual to go through?....Or am I just blowing smoke at myself, thinking this would make any difference whatsoever at this point?

....And billh, I contacted the General Motors Research Center....They said chrome air cleaner covers have very, very little to do with better mileage!

FWIW - One man's experience - I switched to synthetic on my previous S.O.B., and noted no change in fuel or oil mileage, or operating temperature, over standard petroleum oils. Synthetic is, however, a lot more expensive, and I switched back.

I'll continue to use regular oil, changing at 3K miles, rather than risk the longer change interval recommended for synthetics. But then, I'm an old man, and set in my ways.

When I changed to Mobil One, the directions said there's no problem with the switch, and regular oil can be added to the synthetic if necessary. Just do a standard oil & filter change.

The Tech Topics column in the August 2004 issue of the Good Sam Highways magazine says the same thing answering a correspondent's question.

My single experience doesn't mean the experts and the salesmen are wrong, though I know of no real-world tests that would prove or disprove the superiority of synthetics. That would take two or more vehicles operating identically side-by-side for tens of thousands of miles, one with, one without the synthetic.

Lab tests seem to demonstrate the superiority of synthetics. I don't know if they're enough superior to justify the added cost. They might be good insurance in a really marginal situation when factors like neglected cooling systems, poor timing, poor fuel, or neglected oil changes stress your engine, but it's cheaper to keep that stuff up, than relying on synthetic oil to keep you out of trouble.

If you've got the money and it makes you happy, go for it. It certainly isn't likely to hurt.

Wal-Mart sells a synthetic for about half the price of Mobile 1, Might be comming down the same line, who knows

Without a doubt, there are MANY real-world tests that show synthetics to be VASTLY superior. One can go literally a million miles without ANY signs of wear, and I kid you not. I was a service mechanic at the trucking company Sea-Land in the 70's, in Fairbanks, Alaska. MOBIL was testing this new synthetic that was to became MOBIL 1. (It was CLEAR! they put the color into it to make consumers think it's oil!) Anyway, they had four new trucks that ran it, and they would tear the engine every 50,000 miles. No wear. Ever. No shit. The test stopped at 1,500,000 miles. Even the crusty old crumudgeon mechanics were impressed.

Now, if you have a leaker, it gets pretty expensive to run synthetic... but you will not have a wear issue with your internal engine components.

One can get a bit better fuel mileage with a synthetic, .5 to 1 mpg, in my experience.

I used CASTROL Syntec for a brief while, and found that it was not as good as MOBIL 1. I somehow lost more to blow-by, or something... The CAT 5-w-50 synthetic that you can buy at a CAT dealer is actually a MOBIL product, (MOBIL DELVAC 1) but the base stock is different than the consumer MOBIL 1, and, IMHO, superior. It's 5-w-50, and well worth it. For you DIESEL runners, for sure. You can also get it, DELVAC 1, at truck stops. Same stuff. You WILL get hundreds of thousands of trouble-free miles running a synthetic. Cheap insurance in my book.

Now, you STILL have to run your machine to keep condensation away from your engine and such. But you CAN extend the oil change intervals with a good synthetic. MANY chemical analysis tests have shown a good synthetic's lubricity to be still fine at 10-15-20,000 miles. It't the FILTRATION that can fail one if they assume that "since I put in synthetic I can extend service periods". Well, you CAN, but NOT the filters! I change my filters every 5k, the oil every 10k.

Good luck!

Dute

Chevy puts Mobil 1 in the Corvettes.

The harder you run it, the more it benefits from synthetics. Particularly cold starts and hot hot hot running.

My jet boat motor is a full roller 502. It really likes Mobil 1. My street vehicles get it, too, but I can't say I notice any difference, as they don't work as hard as the boat.

Thanks to all for the feedback.....

Based on duteman's informative anecdotes, and the fact that billh didn't say NOT to do it, I'm gonna switch over to Mobil-1 and see if I notice a difference......If I could see something between 1/4 & 1/2 mpg increase, that would easily wash-out the quart per 1k that doesn't burn or leak, but mysteriously disappears (figuring dino @ $2 and synthetic @ $8).........Keeping filter changes @ 3k and moving oil changes to 6k with Mobil-1 further reduces increased costs of sythetics. (Besides, motorhomes are meant to consume disposable income, aren't they?....)

SIDEBAR: Using many of the suggestions from this site & elsewhere, I also did the following:

1. Ran a Zerex chemical flush thru cooling system. (the leave-it-in & drive-it-6 hrs-type)

2. Plumbed-in a back-flush system....back flushed until clear discharge....

3. Re-filled with 15-20% antifreeze (Gotta remember THAT this fall!), filtered rainwater and two bottles of Water-Wetter.

4. Through doghouse, back-washed radiator with alum. siding cleaner & water with pressure washer & "medium" pressure nozzle...then thru the front again......

5. Installed baffle for right engine bank to channel air across manifold rather than escaping thru fender well, i.e.: piece of angle riveted to underside of floor, baffle plate attached to angle with wing-nuts to facilitate access for plugs, wires, belts, etc.

6. Replaced hoses, thermostat & rad. cap.

RESULTS: I'm impressed!.......Since I did all of the work at one shot, I cannot deduce what helped and what was a waste of time, but operating temps noticeably dropped. I don't have an after-market temp gauge installed (yet), but the OEM Chevy dash gauge used to ALWAYS indicate a little over halfway between middle mark and the high mark......Now it indicates only a needle-width on the high side of the middle mark....I'm guessing a minimum of 20 degrees difference.

ONE QUESTION REMAINING: I'm told that I will definately know when the fan clutch kicks in by the noise....Yet I've never heard it myself on this unit....Maybe it never got hot enough?....Or, maybe I need to check out the clutch itself. Is there a simple static-type test to verify clutch operation? They don't give these things away, and before I spend the bucks for a blind, feel-good replacement, it would be nice to know if it's even necessary.....

Again, Thanks for all the feedback....To paraphrase, owning a 25 year old Barth isn't a destination, it's a journey.........

Lee, a friend of mine that bought my Apollo w/440 Dodge claims 10 degree lower engine temperatures by using "Royal Purple Ice"
http://www.royalmgi.com/purpleice.html


------------------
Larry and Heidi from CA

I have replaced several fan clutches always with an instant improvement in cooling.

Analysis of the "failed" clutches showed no problems, yet they were bad. I took one one to an "expert" who spun it and announced it was "fine".

My take is that there is no way to test a clutch to see if it is bad. Just replace them every 50K miles or so. They aren't really that expensive.

BTW, I have also replaced thermostats, radiators and water pumps with "heavy duty" components with no noticable effect. Only increasing the air flow through the radiator seems to improve cooling.

Lee, sounds good, but I suspect you are still running a little hot. My fan kicks in before my needle hits the half way mark, and the needle never gets above half way. Often, the fan will cool the engine down and it will get quiet again for a while. The engine normally runs at half way between middle and cold.

You can check your fan clutch by putting a piece of cardboard over the radiator and letting the engine get hot. The fan should roar like a P-47 when it gets hot. My experience with other GM vehicles has been that the fan kicks in when the temp is around 210 degrees. The factory clutches seem to be the best, but only last a few years. I am informed by a shop that does Jaguar conversions that they have had premature failures with every other clutch they have used. The factory gauges are not temp calibrated, and cannot be used as a serious reference.

I like to stick in a mechanical 270 degree needle sweep gauge as a temporary check just to see what is happening.

Dute, I would be interesting in hearing more on why you think Delvac 1 is better than MObil 1.

Thanks everyone......

OK, based on suggestions, I'm pretty well convinced my fan clutch is over-the-hill.....

Without a Chiltons, I looked it over by Braille to plan an R&R....questions:

1. I SEE 4 bolts connecting fan blades to back of clutch.....I FEEL what appears to be a bi-metallic theromostat winding on front center of clutch....

Logic says there must be SOMETHING for a clutch/pump shaft lock-up to happen, yet I don't see anything....behind the theromostat maybe?...If so, what is it?....And for the BIG question:

2. Is this clutch replacement gonna happen fairly easily, without shroud/radiator/plumbing removals, or am I in for a BIG, BIG job?

The fan, as you noticed, bolts to the clutch with four bolts. The clutch bolts to the water pump flange with four nuts. 1/2 inch wrench, I believe. Leave the belts tight until you have everything loosened. The shroud is in two halves, upper and lower, held together with staples or clips. Taking off half the shroud makes it easier.

While you are in there, take a good look and feel the hose from the water pump to the intake manifold. Heck, it is just a few more bolts to replace the water pump with a Moroso or Edelbrock high flow one. Oh, yeah, new belts are good. Carry the old ones as spares in a Foodsaver vacuum bag.

Thanks Bill!.....This job may have a slight complication, but it still appears do-able..

The shroud is definately one-piece, and I'd much prefer to leave it alone, BUT,

Since the ID of the fan mount portion is larger than the shaft flange, it appears:
1. Unbolt clutch from fan blades,
2. Unbolt shaft flange from shaft,
3. Snake shaft flange thru fan mounting hole, leave blades parked at bottom of shroud.
4. Maybe remove belt & top rad. hose to retrieve clutch/shaft assembly out of doghouse......
5. Swap-out clutches in the comfort of the shop and then reverse process.......

I'm still confused as to what the clutch to shaft connection will be, but I'll know soon enough I guess........

I'm assuming there's no need to mark any
thing for re-assembly for any balancing issues......

Pump was replaced at 60k mark, so if shaft movement feels good, I'm gonna assume no-harm, no foul.......

Thanks for the wisdom.........

In at least one case I remember, the thermostat coil had a hook bent outward on the end. As the coil got hot, it uncoiled and expanded dragging the hook around to snap into a slot in the outer rim, and making a solid mechanical connection between the fan and the clutch. When it cooled, the coil contracted, pulling the hook out of the slot to let the fan free-wheel..

QUOTE:
"4. Maybe remove belt & top rad. hose to retrieve clutch/shaft assembly out of doghouse......
5. Swap-out clutches in the comfort of the shop and then reverse process.......

I'm still confused as to what the clutch to shaft connection will be, but I'll know soon enough I guess........"


The clutch and the shaft are all one unit. The rear end flange bolts to the water pump, and the front end bolts to the fan.

I suspect that if you look at your shroud carefully, you will see a horizontal seam halfway down joined with rather heavy wire staple-like thingies.