Gas engine life today vs yesterday?

skolbe said:
BMW has their cars coming in at 16,000 miles for oil changes, the computer adjust for driving conditions.
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I believe a lot of the marine engine failures at 1200 hours is related to driving conditions and how the engines are cared for. I see lots of old boats running around this lake that have original engines with little or no work done on them other than oil and filter changes. My son has his eye on an old 26' Slikkcraft that is original that he wants to buy for his cottage on Lake Tahoe. The boat is probably 40 years old but owned and maintained by a former local marina owner. I would not hestitate buying the boat because I know its history.
 
How exactly does an engine die "of old age?" To me, a corroded and rusted out intake manifold doesn't qualify as death by old age - that's more death by neglect. This is a part that is replaceable and should be replaced at a certain point. The entire exhaust system on these engines are fraught with weak links. Neglect it, water gets in where it doesn't belong and the results are catastrophic. So assuming you do all the maintenance and replacements you are supposed to do and nothing fails prematurely (a stupid gasket on the Merc exhaust, for example), why does an engine get put out to pasture?
 
rondds said:
How exactly does an engine die "of old age?" To me, a corroded and rusted out intake manifold doesn't qualify as death by old age - that's more death by neglect. This is a part that is replaceable and should be replaced at a certain point. The entire exhaust system on these engines are fraught with weak links. Neglect it, water gets in where it doesn't belong and the results are catastrophic. So assuming you do all the maintenance and replacements you are supposed to do and nothing fails prematurely (a stupid gasket on the Merc exhaust, for example), why does an engine get put out to pasture?
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So we come full circle here and go back to the thread “later year or less hours”. I have been concerned about the number of hours I have put on my boat. She is a 06 and I already have 430 hours logged, but I can tell you this, the boat is immaculate. The inside looks and smells brand new, and as for the mechanics I keep up on all maintenance and preventive maintenance. So in keeping with the engine life being everyone’s concern with buying a boat with high hours, if the engine has been properly maintained, high hours should not be an issue.

I just keep telling myself that, and keep running the boat.:thumbsup:
 
I don't care much for that test. Around 1996 the most common taxi cab was the Ford Crown Victoria. They must have looked at older model vehicles with the old 5.0 push rod V8. That engine used flat valve tappets. The later models had the newer 4.6 SOHC V8 which had roller followers.

Flat tappets don't wear evenly. They usually wear concave. Don't know how they measured that wear, but I'm suspect. Measuring weight loss from the connecting rod bearing is interesting, but a better measurement would have been to compare the change in journal clearances. Also think they should have checked for cylinder wear. The language used is imprecise. For example, "the combined wear for both parts [camshaft and tappet I presume] averaged only 0.0026 inch" which sounds really good. However, according to Ford's service specification manual for 1990 the 5.0 V8, which states, "Allowable lobe lift loss: 0.005 Max" Now assuming that they were measuring lobe lift loss, which I assume they must have been since anything else is meaningless, that means that the camshahft was more than half-way to being out of spec in just 60,000 miles. That seems significant to me.

But testing over such a short period, just 60,000 miles, is nothing. Other than a junk GM 4.3L V6 that was in a late 70s Buick my Dad used for work, I never saw an engine give out in less than 100,000 miles. They needed to run that test 3 or 4 times as long.

That said, that Ford V8 in taxi cab tune, it's exactly a highly stressed engine living a hard life. Idling doesn't hurt an engine that much. Worst thing is that the oil doesn't get hot enough to "burn off" contamination. But that wouldn't be the case here since the engines are usually running.

Anyway, marine engines work a lot harder. Higher power levels mean higher peak cylinder pressures, which translates into ring and cylinder wall wear. That test didn't measure that. Also the measure of better oils and more frequent changes becomes more evident in more severe usage. For example, turbocharged engines can be hard on engine oil since the oil lubricate the turbo's bearing that's just a fraction of an inch from the red hot exhaust housing. Use of poor quality oil or the wrong oil can cause coking and premature failure. Also, see the recent case of the the Audi/VW 1.8L turbo engine oil sludge problems and also Toyota.

It's not that simple.

Best regards,
Frank
 
There are some big disadvantages in newer engines. They have learned how to squeeze tons of extra HP out of the same blocks. This makes them wear faster. Also, they have squeezed weight and/or dollars out of the construction - 8.1 with aluminum manifolds.

I would imagine that if you don't push them too hard and take really good care of them (don't take chances with cooling/pulling manifolds...), then they could last quite a long time. This is all under your control.
 
Frank,

Thank you for weighing in on this.

I hold your posts and opinions in high regard.

So what is your opinion on 100% pure synthetics? Under the same use will my engine life be about the same or higher on average?
 
fc3 said:
But testing over such a short period, just 60,000 miles, is nothing. Other than a junk GM 4.3L V6 that was in a late 70s Buick my Dad used for work, I never saw an engine give out in less than 100,000 miles. They needed to run that test 3 or 4 times as long.


Best regards,
Frank
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:wow: Oh No!! Are you saying the 4.3 back then was junk and better today? Or are you saying they are all junk:huh: I'm about to pull the trigger on two of them and if they are "junk" I would like to know before I get them!!
 
Frank,

Thank you for weighing in on this.

I hold your posts and opinions in high regard.

So what is your opinion on 100% pure synthetics? Under the same use will my engine life be about the same or higher on average?
Click to expand...

Good God don't make his head any more swollen than it already is! :grin:
 
Hampton said:
There are some big disadvantages in newer engines. They have learned how to squeeze tons of extra HP out of the same blocks. This makes them wear faster. Also, they have squeezed weight and/or dollars out of the construction - 8.1 with aluminum manifolds.
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Bogus. You've been reading too much Pascoe. Back in ye olde days, that was a truism. Any engine that was close to one horsepower per cubic inch was "on the edge" and "wouldn't last." However, a combination of better metallurgy, more careful machining, closer assembly tolerances, and better lubricants, many engines produce 1 or more hp/cubic inch. I've three V8s here that are slightly under, at, or slightly over that "magic" ratio and all have been trouble-free. The highest mileage of them is currently around 340,000 and I do use all 300 hp pretty darned often.

floriduramax1 said:
:wow: Oh No!! Are you saying the 4.3 back then was junk and better today? Or are you saying they are all junk:huh: I'm about to pull the trigger on two of them and if they are "junk" I would like to know before I get them!!
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Back then they were awful. Basically, Buick "engineers" sliced off the last two cylinders of a small block V8 and threw it into production. The one we had had lots of bottom end problem. The first time it died, the crankshaft wasn't being located properly and was sliding fore and aft, which tore things up pretty badly. I think that was around 60,000 miles or so. The engine was completely rebuilt. Before my dad put another 20 or 30K on it, the engine threw a rod though the block and that was that. Somewhere in the 80s GM redesigned the bottom end. The put a better designed crankshaft in, instead of the shortened V8 one, for example. It's a decent engine now. Anyway the point that I was making was that even with regular 3,000 mile oil changes, that engine still failed twice. Not much you can do about that, sometimes.


Presentation said:
Frank,

Thank you for weighing in on this.

I hold your posts and opinions in high regard.

So what is your opinion on 100% pure synthetics? Under the same use will my engine life be about the same or higher on average?
Click to expand...

Thanks. You check is in the mail.

I think if you need synthetics, then you should use them and they'll do you good. Turbo engines, for example, probably should use synthetics. Any engine with a "reputation" of sludge formation, should use synthetics. If the manufacturer recommends or requires a synthetic, then you really should use one. Otherwise, it's a matter of how much overkill you want to pay for.

I've been running Castrol mineral 5w-30 oil in the Navigator since new and changing the oil every 3000 or so miles. It's still running well with over a third of a million miles. I had to pull the rocker covers off a couple of years ago to replace the gaskets. Everything inside was clean. No sludge or deposits; everything was stained light tan, the color of new engine oil. The dual overhead cam looked good, the followers, chains, and bearing appeared fine, too. I couldn't measure any wear without doing a disassembly, but I didn't see any need to do so. Good enough in my book. Now on the other hand, I'm running Mobil One synthetic in my wife's Jaguar. It doesn't require synthetic, but it can't hurt. It's an expensive engine, and she doesn't drive it that much so the cost is minimal despite that a change is seven quarts. If I were to buy one of those cars with that new twin turbo V6 that Ford is building, I'd definitely run Mobil One. Replacing a turbo isn't cheap. Replacing two at a time would be insane. Synthetic oil is cheaper.

There's one other consideration. Some synthetics tolerate water better than others. I think that the special oil that Polaris required for their four stroke PWCs could tolerate a bit of water in the oil and still lubricate properly. I don't know if that's true or not. But I suspect it from some things I remember reading at the time. Doesn't matter now. That engine blew up because the manufacturer in Germany didn't plate the cylinders right. So anyway, water tolerance might be a consideration in a marine application. I just don't know if that's applicable or not. Your mileage may vary. I run Merc's regular 25w-40 mineral oil in Just Ducky's 454s,

Best regards,
Frank
 
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Hi Presentation. I think your would engine would have higher on average because pure synthetics are good than the other. :D
 
The reason synthetics are GENERALLY better than dino oils is the uniformity of the carbon molecules. That being said, a high quality dino oil with a really good additive pack{like Shell Rotella T} is better than a cheap "synthetic" with a poor add pack.... how to tell the difference??? There is some good comparison tests done by the motorcycle industry {google it}. Also, if you are running raw water cooled engines, they are thermostated much cooler than closed cooling, and the dino oils work better because they hold uncombusted hydrocarbons in suspension better{byproduct of a cold engine}. I use merc semi synth in my 94 vintage 340 hp 454's and have 1500 hours, no oil consumption, no blowby.
just my .25 cents

Cheers
 
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Being a Diesel guy, the info on gas powered engine do not completely apply to diesels. It doesn't matter how gooder you feel about your car oil, A marine diesel operates on a completely different level.

Diesels now are running lower sulfur fuels than ever before. This means different acid levels in the oil than in gas engines. Many are using C-tane boosters now which affect the performance of the oil. Torque bands are greatly different between gas and diesel. Just because your diesel runs at half the rpm doesn't mean you can go twice as long on an oil change or that you can use a cheap oil.

Bio fuels are also now available for diesels. We have a customer that runs 50-50 bio in the summer and 100% veggy fuel in the winter. He changes his fuel filter twice as often however his oil filter at regularly manufacturer scheduled intervals.

NOTE: If you plan on running ANY bio fuel, get rid of your rubber hoses and go to Synflex type fuel lines.

I would say that there are only 2 reasons to move away from manufacturers recommended oil.

1. Operating conditions such as load change, fuel additives, or engine age (moving up a wt class)
2. The recommended oil can't be purchased in your area.

If you are changing oil brands because of price then sell your tub and get a jet ski. If you can't afford quality oil then you can't afford to boat.
 
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OldSkool said:
If you are changing oil brands because of price then sell your tub and get a jet ski. If you can't afford quality oil then you can't afford to boat.
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Don't know about that. The synthetic oil for my departed but unlamented Polaris PWC was $50/gallon and the stuff for the Sea Doo PWC is, I think $40/gallon. I forget because the dealer did the first change and I bought the shop manual and a few other things when I did last year's change.

Can't use full synthetic in the Sea Doo because the supercharger has a wet clutch and the full synthetic is too slippery. That causes the clutch to slip too much and wear,
 
fc3 said:
Don't know about that. The synthetic oil for my departed but unlamented Polaris PWC was $50/gallon and the stuff for the Sea Doo PWC is, I think $40/gallon. I forget because the dealer did the first change and I bought the shop manual and a few other things when I did last year's change.

Can't use full synthetic in the Sea Doo because the supercharger has a wet clutch and the full synthetic is too slippery. That causes the clutch to slip too much and wear,
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i run synthetic in my motorbike with a wet clutch, you just have to make sure it does not have any molybdenum in the oil, commonly refered to as "mileage improvers",or "epa approved" etc
 
While gas engine improvements have undoubtedly taken place, I believe that one of these "improvements" (catalytic converters) has a detrimental effect, at least on older engines.

We just replaced the stbd engine on a 1995 EC with a reman. 7.4L Generation V (flat tappet?) longblock, due to a worn cam. After some investigation, I have found that the auto-oil industry has twice reduced the levels of zinc (or ZDDP) to meet the EPA demands for catalytic converter life. This didn't really effect marine oil until recently when they started putting cats in boats (assuming you were using marine oils).

I just put QuickSilver/Merc 4-cycle 25w40 marine oil in the port engine for the winter, and wonder what I should plan to do from here. My thought would be to use the QuickSilver/Merc 25w40 (dino) in the reman. for break-in (20 or 40? hrs), then switch to a full synthetic (QuickSilver/Merc 20w40 or Mobil 1). But my big concern is no full synthetic will have the old levels of zinc to protect the cams. And Mobil 1 won't have any marine additives. I am close to adding some zinc (EOS or Redline?), but then I risk over compensating or screwing up the original additive package. Maybe QuickSilver/Merc synthetic blend be a good middle ground, or is it one of the lower quality "hydro treated" synthetics?

Has anyone else heard of the lower levels of zinc in motor oils, and how that is expected to work with the older, non-roller cams? An email asking Mercruiser about the current levels of zinc in their oils was of no help. They just cited from their website. Any oil comparisons would have to be recent, as the oil formulations have changed. Even the well trusted Rotela has been changed.

Thanks for the great information,
John

PS Fresh water on Lake Michigan, now and the foreseeable future
 
I use Rotella Triple-T 15-40 in my engines. I also use a zinc additive (Rislone) due to the lower amounts of zinc in the oil. I change my oil every 50-60 hours of use. Doesn't burn or leak a drop. Nice strong oil pressure.
 
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