Is Synthetic worth it?

I should start this out by saying that I am extremely particular on all my fluids in any machine that I own...

I was looking at this engine oil here: Z-ROD® 10W-30 Synthetic Motor Oil

I've seen it said that flat-tappet cams need to have ZDDP in order to reduce wear. I also know that '85 was the first year (from what I've seen) for roller cams, which means that my '84 318 still has a flat tappet cam in it. For the last 6 years (and 20,000 miles) I've religiously changed my oil every 3,000 miles, but I've been using real cheap Mobil 1 10w30 conventional. Do I need to worry about ZDDP? Is a synthetic overkill? I figure that using really good oil is cheap insurance. Opinions? Thanks guys.

I use synthetic in every thing I own, motor, trans, axles and hydraulic fluid. Even the air compressor in the shop.
The Amsoil ZRod is great for flat tappet cams, use it in my junk. I would run it for 5 to 6K before dropping out of my driver.

The 318 has very low spring pressures, and a low-lift cam, so IMO, the issue of dropping lobes should not affect it...especially in a long-ago work-hardened cam, IMO.
I would continue to run dyno oils
because
unless your engine has relatively new gaskets in it
the Synthetics will find every little crack and crevice to seep out of, and make a mess of your engine bay, and undercarriage.
As to are they worth it; In a modern EFI engine yes, because in this application the oil-change intervals can be greatly extended, reducing the annual cost to near break-even. And in the mean-time, they do a better job of lubricating.
EFI make the use of synthetics possible, even advantageous.
If the cost is 3times as high but you can drive 3times as far on it, then you break even on the cost of the oil, and save on the labor.
But in a carby-application , you cannot extend it that far, cuz the oil gets polluted much faster. In your case,I would not double the intervals. Maybe plus 50% might be Ok.It's probably a case by case decision. This makes it very expensive. And if you have to add oil in-between,then what? Are you gonna remember to add synthetic? And if you don't then you're gonna need to drop it early; making it yet more expensive.

I would consider a old carbed car motor on synthetic as junk.
Nothing I'd buy.

This is a subject that I've seen on every forum I've been on, automotive and tractor. What it comes down to is personal preference, I like the fact it works better in extremes, cold, heat, o power and efficiency.

I have been using synthetic for twenty five years and never had an oil related failure, prior to that I had two 440s take out mains one inc. crank.

My introduction to synthetic was gear oil was my Volare breaking the 4.88 pro gears in the
8 3/4 at +-150 passes. A friend of mine told me about synthetic gear lube and now I pull the gears at 500 or so runs and in go a fresh set. That was in 1992 so I'm a believer.

When men like this talk Mopar, I listen and learn.

This guy is so cool and approachable.

I agree with AJ - if the motor is already well used then stick with the conventional lest you like oil leaks. ZDDP shouldn't be an issue on a motor like that. If it was fresh rebuild, synthetic all day long.

AJ/FormS said:

the Synthetics will find every little crack and crevice to seep out of, and make a mess of your engine bay, and undercarriage.

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That was one fear that I had, so thank you for solidifying that. I don't currently have any major oil leaks, and I don't have to add any oil between changes, but 90% of the gaskets are original.

Thanks for the clarification guys. I'll stick with a high quality conventional. I've so far been happy with the Mobil 1 oil. I know the inside of my engine is clean, because when I replaced the valve covers and gaskets the rockers were perfect. The cam and lifter valley was very clean from what I could see through the distributor hole, and when I put my borescope into each cylinder, there wasn't much carbon on the pistons and I could still see cross-hashes on the cylinder walls. It's in good shape for 75,000 miles (which is still pretty low). I'll just keep on with what I'm doing.

Since I don't get that many miles on the summer coupe, my oil changes can get kinda stupid.

I like fresh oil before I store it for the winter, so I've done oil changes at 750-1000 miles.
I buy my Baldwin oil filters by the case, so I always have one.

If you want something a tad "better" (up to you to decide what makes it that) you could always try a blend. Most folks say they are a waste of money, and it used to be that in order to call an engine oil Synthetic the mfg had to have 5% synthetic by volume, and yet the prices they charged were near sythetic level anyways...yeah, total money-maker for them! Not sure if that is still the case, nor whether the US regulations are/were any differen then our Canuck stuff. However...Valvoline (as well as other makers) do make these blends that are specifically meant for high-mileage engines. They attempt to avoid the "leaks everywhere" problem with specific additives that play tricks with gaskets, in a good way that is. The benefit is that you do get additional protection. Having said that, in your applications, as the guys have pointed out, you probably do not need that extra layer.

For my part, I run the Valvoline Racing (VR) motor oils in my 360. That is still a flat tappet hydraulic cam, needs the added zinc and phosphorous and given about 320ft-lbs of spring pressure at max lift I would rather play it safe.

For anything else, like a performance roller cam motor, or all my daily drivers I ran synthetic only! Heck, the Jeep is a 0w20 oil, V6 only, the wife wouldn't let me get the V8...grrh....still it's a Trailhawk and a pretty ass-kickin' ride!

Synthetic is a superior product to dinosaur oil. Period. In the late 60's and or early 70's Mobil1 synthetic advertised there oil can be run "Around the equator 5 Times" as is showed a car circling a globe and a 6 digit odometer (Unheard of at the time) wrapping up to 125,000 miles. Can you imagine!? Changing oil and plugs together at 100k, cause your a fanatic about oil changes!? LMAO! I value AJ and every word of his as gospel. But I have never noticed or heard of anything that developed oil leaks from an oil change, unless there was no oil to drain out first. Pretty sure the syn/dino molecules are equally sized, and additive pkg goes in both. Syn oils maintain viscosity porosity over a much wider temp range. Syn can't thin to the point it flows like water at any operating range to my knowledge. Its not acidic or alkaline. I don't mean to argue or question. I just cant find an answer how or why syn would cause or develop a leak dino oil wont find or make. I have huge respect for AJ and everyone else. But Id love to get your thoughts and insight.
Your question was about zinc and flat tappets. Its not good on Cats. Not recommended for Cat equipped cars. You should be just fine on reg, syn or blended oils. I wouldn't buy syn, for money reasons to use in your circumstance. Its just more expensive and you get none of the benefits you pay for with syn.

4speedjim said:

I wouldn't buy syn, for money reasons to use in your circumstance. Its just more expensive and you get none of the benefits you pay for with syn.

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Thanks for that. It's really good to hear. I've also heard about cats and zinc having an issue. I'll stick with my dino oil. Like I said above, I know that the inside of my engine is clean. I'll keep on with what I'm doing.

I haven’t seen or heard anything about synthetic oil causing oil leaks, before.
Not saying it will do it – but logically, I don’t see how it can.

My opinion is: “synthetic oil is better than conventional oil – but” (and a big but) the reason we change oil - is to get rid of the contaminates. Contaminates that is too small for filter to catch, that is. I use the term “contaminates” generically and it means anything that didn’t come from the oil container, initially.

If there was a way to keep contaminates out of the engine oil, thereby allowing the oil to stay cleaner, then I’d be all over synthetic oil like “kids over ice cream”. On top of dirt, carbureted vehicles just put too much “fuel” in the oil, as well, when engine is cold.


I change the oil in everything in my fleet every April and October – regardless if the vehicle wants it or not (and lawn equipment every April). That is about an average of 5k miles per vehicle between changes.


Transmission and differentials – are close to the same. The reason to change fluids is to get rid of contaminates.
Transmissions (automatic and manual) as well as differentials get hot when in operation. All three items have external vents on them so as unit gets hot, built-up air pressure does not blow out a seal (or something). The excess "hot" air exits via the vent.
The problem is as unit cools down, outside air gets pulled into the same unit. This outside air could contain high humidity, dust or even bugs, sometimes. If a person could install vent air filters for each, then the fluid change intervals could change – but cost for such a filter and modification time, might not be worth the cost of fluid changes.
In the case of automatic transmissions, a person needs to adjust the bands about every 30k miles, anyway – so cost of synthetic ATF seems like a waste, to me.


NOTE: I am not saying not to use synthetic fluids – for there is no question in my mind they are superior to conventional fluids. On our cars, especially for those who have not upgraded to fuel injection yet, and thereby need engine oil change more frequency due to contaminates - the cost of synthetics do not appear to be cost effective. To me.
The newer vehicles – the cost disadvantage vs. fluid effectiveness – synthetics make a lot more sense.

NOTE: I will support anyone pushing for synthetics – AS WELL AS I will support pushing conventional fluids. This is not anything worth arguing or debating about, in my mind. I will save my energy to argue other issues which I feel more strongly about. The type or brand of fluid is not worth the effort to argue about.
Now well maybe the frequency of fluid changes and/or viscosity, might be worth the effort . . . maybe.

Most people I know of are already set in their ways on which type of fluids – except for those who are not knowledgeable on the subject and are asking for more details.
I’m not going to push either way, only present the facts, as I know them.
BudW

As I said before this is a personal preference subject, one thing that should be noted is the oil filter should be changed at 3 to 5K depending on the type of driving done.
Also synthetic does free up a percentage of HP.

Synthetic will start flowing faster on a cold engine.

For Diffs, ATF, PS that seldom get changed over most cars lives I think its money well spent. It will free up 8-10 HP with a full synthetic change on the dyno.

I use synthetic wheel bearing grease also.

I have been using regular oil, since new, and have over 300,000 miles on my 318. It still burns virtually no oil. But for the seventeen winters, that it was my daily driver, the block heater was used on cold nights.

Use whatever you think is right. Most oils, synthetic or conventional, perform so well, that there really won't be any difference to the engine, as long as oil change intervals are reasonable.

I personally believe that the engine really only needs what the engineers who designed it say it does. Using better than it was designed for is fine too, but it is not REQUIRED by the engine.

I do believe that non-roller lifter engines require higher levels of ZDDP than is currently provided by any API SH or newer class of oil. I do use hot rod oil (oil with a high level of ZDDP) in older engines. There have been shows on Velocity that have shown cam lobe wear attributed to lack of ZDDP, and I have seen personally valve recession caused by using unleaded gas on older engines without hardened valve seats. Not everything is an old wives tale.

Leaks with synthetic oils in the earlier years of synthetics were not caused by the oil itself. It was due to the additive package in the early synthetic oils causing cork gaskets to shrink slightly. Both the additive packages and gaskets have changed a lot since then.

4speedjim said:

I value AJ and every word of his as gospel. But I have never noticed or heard of anything that developed oil leaks from an oil change, unless there was no oil to drain out first. Pretty sure the syn/dino molecules are equally sized, and additive pkg goes in both. Syn oils maintain viscosity porosity over a much wider temp range. Syn can't thin to the point it flows like water at any operating range to my knowledge. Its not acidic or alkaline. I don't mean to argue or question. I just cant find an answer how or why syn would cause or develop a leak dino oil wont find or make. I have huge respect for AJ and everyone else. But Id love to get your thoughts and insight.

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Jim,
Thanks for the kind words...... but
I didn't say synthetics will cause a leak ,I did say
"unless your engine has relatively new gaskets in it,the Synthetics will find every little crack and crevice to seep out of, and make a mess of your engine bay, and undercarriage."
Therefore if the engine is tightly sealed, it will not leak.
But you know how hard it is to seal up those 4-bolt valve covers, and all their grommets and breathers; and the corners of the intakes and oilpan; not to mention the intake bolts.And as a high-mileage engine starts making crankcase pressure, it just gets worse; and this is a 1984 model .