Synthetic oil in older engines

Quite a few of you guys seem to be down on synthetics, and I am not sure why, other than being stubborn. Synthetic oils are available in most of the common weights, and their superior lubrication abilities make them even better suited for older engines. And where did the "pre-90s" thing come from? Sounds like that one was pulled out of thin air.

Before you go and flame me about tolerances and worn out parts- that is all the more reason to run a synthetic oil. Synthetics coat the parts better than conventional oil and they don't break down like them either, meaning the oil stays usuable longer in more harsh conditions. I use Royal Purple in all my engines, old and new.

If you have a legitimate arguement for not running synthetic, lets hear it.

 

I think you've hit it right on the head, much more superstition, habit, and 'I think" than actual research and education- you think this place is bad, you should hear some of the old fartz on the antique tractor forums get wound up & shout over this, it's hogwash, all a conspiracy, owner's manual (from 1939 LOL) says 30wt non-detergent and had good luck with that...
Do a little actual research, and syn looks pretty good- and for some reason, many of the spendy high-end new cars come with syn like Mobil1 from the factory
I started using Mobil1 in one of my Indians in '01, the oil temp dropped 10 degrees, and I had to slow the idle speed down, it actually started idling faster, and the engine is spotless inside
And yeah, better put your helmet on and prepare for incoming...

 

You won't hear any gripes from me... I love the stuff!

 

Well the regular oil is cheaper than the synthetic oil !

Really most of the problems are due to flat tap cam engine and the newer synthetics didn't have the zinc in the oils we needed . I am using a synthetic oil in my new flat tap engine and is a 10w-40 with the ZDDP in it for the cam . Amsoil has a synthetic 10w-40 oil with the zinc in it to protect the flat tap cams now . That is the biggest problem with the newer oils made today . They don't have the zinc we need for our flat tap engine so we have to use some of the special older oils that protect our engines ! There are a few out there that has enough zinc in them but all the new synthetic oils don't but a couple .
So now you know why we bitch about the new synthetic oils !

Retro Jim

 

also the molecules for synth are smaller, so if it leaks with regular oil its really gonna leak with synth, and if it doesnt leak with stadard, it might start with the fake stuff. However if synthetics dont run out every pore, no problem using it at all.

 

Synthetics are great, but I think the scary part is the lack of zinc (ZDDP) in street blends under 20W50 (considered racing oil). This can be dodged by using a 'racing oil' as labeled by the feds. The Brad Penn oils are considered 'racing oil', even in 10W30.

The other problems were with gaskets leaking on older, 'untouched' engines with their original gaskets. These older gaskets and seals would leak & weap after changing from dino to synthetic. Not much of a problem if the engine has been rebuilt.

Personally, I'm not much for 'brewing' my oil with zinc additives after I get my engine together. I'll start with some Brad Penn and see from there. For the record, my '01 Ranger has 271K with synthetic oil changes every 5K.

 

I have run full synthetic in the OT/DD for the last 157,000 miles. I change it every 10,000 miles, or once-a-year, whichever comes first. The compression is within 2psi of where it was when it was brand new.

I had to change the oil pan, due to a rock hit, and it was nice and clean inside.

 

OK, Here`s your reason: I built a mild chev 383, broke in the cam, changed to fresh dino oil. drove it 2000 miles and changed to Mobil 1...as good a synthetic as there is. I thought I was doing myself a big favor. Drove the car another 14,000 miles changing oil at 2000 miles each time. At 16,000 miles I lose two lobes on my camshaft....not at 2000 miles, at 16,000 miles. There is no zinc in synthetic and you take a chance of losing a flat tappet cam.
Now I use dino oil with a comp cams additive that is loaded with zinc. Good luck

 

I understand that the newer engine go higher mileage but that is mostly due to the Roller Cams & Roller Lifters ! The synthetic oils have been around for a long time but got bigger when the damn government regulated to take the zinc out of the oils ! That is where the problems started . If you have a "Flat Tap" cam you damn well better use zinc oils or zinc additives or your engine will fail very fast !
I have no problems with the synthetics but if you have an older flat tap engine , make sure you have the zinc (ZDDP) additive to add to your oil if it's not in there . Also the racing oils really don't have the proper amount of zinc in the oils and the same for many diesel oils .
Brad Penn , Amsoil w/zinc , Rotella are a few safe ones to go with . If you have a favorite brand of synthetic oil that you really love , just add a bottle of ZDDP to your oil and you will be fine . You can also go much farther in between your oil changes too ! I use synthetic oils in both my wife's and my newer daily drivers !
Comp Cams also has a break in oil and oil with zinc in it for flat taps now !

Retro Jim

 

yep... especially the old rope rear mains...

then there's ZDDP.

The thing is not "don't run it" the thing is don't put it in an older high mileage engine. I still don't break in older engines on it after a rebuild, but will run it after break in. Sometimes the damn synthetics are to damn slippery for everything to seat correctly, especially old technology rings.

 

Some of the Royal Purple is SL with zinc, some is SM w/o zinc. There is 10W-40 R.P. that's SL. Regardless of racing or nonracing label, SM has no zinc & true racing oil has additive package that'd dead by 1500 miles.

 

Has anyone used the mobil1 15w40 or the high mileage 10w40?There website claims these oils have enough zinc in them.

 

I am with the others,,,not in an old engine!
However,,I don't have a problem with using it in newer stuff,,I just have never used it.

Besides,,this is all a lot to do about nothing.
Who the Hell cares if someone doesn't want to use a certain kind of oil?
Just quietly disagree and go on.

Tommy

 

I understand your worries about ZDDP, however, once the cam is broken in, there is simply no need for the extra zinc. I'm not talking abouth the initial 20-minute break-in, I am talking about after the engine has about 500-1,000 miles on it, then you can no longer the zinc to help stabilize the metal, it has already work hardened.

If you lost a cam after 16,000 miles, it was going to go anyway, regardless of the amount of zinc was in the engine, most likely due to bad metalurgy or too much spring pressure.

I certainly agree that you do not break-in a new rebuild with synthetic, it is too slippery, the rings won't seat and nothing with ever actually condition like it is supposed to, I run all my engines with conventional break-in oil, change it after the initial break-in and then run it for 500-1,000 miles and switch to synthetic. There are methods that can be used to break-in an engine on synthetic, but most machine shop don't take the cylinder bores to that level, as it requires exacting tolerances and fine-honing that results in a polished bore. That and a roller cam.

It is not that the molecules are smaller than conventional oils, just that they are more consistent in size and stability. That is part of what helps make it lubricate better; that doesn't mean it will leak out faster. The overall weight and viscocity doesn't change, it isn't thinner that conventional oils. If synthetic leaks from your oil pan, so would a conventional oil; it's just exploiting the same break in the seal, it isn't permeating the gasket material looking for a way out.

Possible side effects of synthetic oils-
Lower oil pressure- You may drop a few psi in oil pressure, this is due to the fact that synthetic oil flows up to 7 times faster than convential oil, and that is a good thing. You don't have to worry about the loss in pressure, the oil lubricates the parts better. This has been proven fact.

More power- simply by switching to a full synthetic, you can gain 10 hp and 15 ft lbs of torque because there is less friction inside the engine.

Lower engine temps- less friction=less heat

In addtion, start up wear and tear is greatly reduced. Because synthetics flow at the same rate when cold as they do when hot, you don't have any issues with pressure or flow in a cold engine. Conventional oils flow at decidely different rates when cold vs. hot. In fact, conventional oil is frozen at -62 degrees, synthetic oils don't.

Synthetic oils are not voodoo witchcraft, they are still based on the same chemicals as conventional oils, but instead of being boiled and mixed together in a refinery, they are the product of complex chemical reactions in a lab. This means that all the molecules are the same size, and there are no waxes, sulphur, or asphalt in them (yes, there is asphalt is in your conventional oil!). These contaminants become the sludge that sticks to your engine's guts, and lead to parts break-down.

In reality, synthetic oil is better for your older engine and those are the facts.

 

It's not about disagreement, it's about dispelling the myths that surround synthetic oils and older engines. Having a dialogue about it doesn't hurt anyone.

 

I have a '77 sbc with approx 40k miles and use the conventional 10w-30 oil. If I went to a synthetic oil should I use the 10W-30 or go with somthing heavier such as 10W 40?
Thanks

 

This isn't an argument so much as a reason I don't use synthetic. I've never had a problem with an engine that was related to the use of conventional oils. Not saying that there aren't some situations where synthetic oil won't provide some benefits over conventional oil. Just saying that the engines in my vehicles apparently haven't needed it since I've had no oil related problems.

Bob

 

I put synthetic in my A100 Van (110,000 mi.) and now it leaks everywhere, I wouldn't recommend it in older vehicles.

 

I'll keep using Brad Penn with lots of zinc, thanks.

 

This is the kind of misinformation that continues to cloud the issue- there is ZDDP in syn oil- at least twice in this thread, it has been incorrectly stated that there is not- but just like dino oil, most shelf syn oils are the low-ZDDP type mandated by Big Brother for use with cat converters- avoid anything with a GF-4 rating- so just like dino, one needs to check the specs (whether it's syn or dino) and either choose one with the proper ZDDP level for flat-tappet engines, or include an additive- again, whether it's syn or dino, same-same, have to do your part and research it- all the oil companies have websites that can help take the witchcraft and voodoo out of this
And the need for ZDDP with a flat-tappet doesn't magically go away after break-in, you need to keep using your oil with ZDDP or an additive for the life of the engine
The research isn't that difficult, one just needs to block out all the hype for a few minutes and check it out- it's this simple- look at the 15W-50 on the chart
http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf

 

I use Brad Penn because of the high zinc content. If cam manufacturers recommend it thats good enough for me. Regarding synthetic oil, the airlines and the military has been using it in jet engines for over 50 years with no problems.

 

I'm not down on synthetics in general, and I'm not an engineer, but I do know from personal experienece that I wont try them in an engine with many miles on it ever again.
Had two cases where I tried synthetics and got different, but bad results.
First case was a big block Ford that had good oil pressure before switching to Synthetic, and never came up again after the oil change. It had nearly 70,000 miles when we switched it.
Second was my '76 Goldwing with 40,000 miles that started smoking on warm up after switching. It would stop after the engine got warm, but used oil until I drained the synthetic out, and returned to straight 30 wt. oil and a new filter. Never has smoked on startup since, and it's been 10,000 miles since I swithced it back.
Do what you like, but I'll keep synthetics for new engines/cars, not my older cars and bikes.

 

If you are a regular oil user, keep track of your gas mileage for a 3000 mile cycle. Then buy the expensive synthetic and a can of STP. Keep track of your mileage for thr next 3000. You are gonna find that after 3000 miles you got the synthetic oil for free. If you go longer on the oil change you save a little more.

I bumped a crater in the road a couple of years ago in my T. It was on an entrance ramp to the Interstate. Dark and pouring rain. After a couple of miles on the highway, the engine sound changed, I thought maybe it's getting hot, temp looked OK, another mile and the valves stared to click, looked at the oil gauge in the rain and 60 and 0 are opposite from each other and I thought it said 60. But it was Zero. Slowed down a little and
made it to the next exit. Lifters were getting really noisy. Parked in a closed gas station, looked underneath and the drain plug and pan scrapped on the ashfalt and the plug was gone, left side of engine so it unscrewed when it hit the ground. But it felt like the treads were fucked up in the pan. Towed home.

Next day, tap the hole, put a new plug, fill with oil and hope for the best. The engine survived 7 miles of highway driving with no oil in the pan. and no damage at all. Thanks to synthetic oil. It's good insurance for dummies like me.

 

After break-in, extra ZDDP protection is simply not needed. Even the experts at Comp Cams agree. Yes, you need the enhanced ZDDP for a new engine, but once it is broken in, you do not need the extra ZDDP additives. To much zinc anc phosporous in your oil actually has the opposite effect, causing more damage. Here is a quote from GM-

"A higher level of ZDP was good for flat-tappet valve-train scuffing and wear, but it turned out that more was not better. Although break-in scuffing was reduced by using more phosphorus, longer-term wear increased when phosphorus rose above 0.14%. And, at about 0.20% phosphorus, the ZDP started attacking the grain boundaries in the iron, resulting in camshaft spalling."

So you see, yes, you need ZDDP, which is still in all oils, it has not been eliminated, just reduced. Once your engine is broken in, you don't need it. However, ZDDP is besides the point of this thread. The point here is that synthetic oils is not the demon that many make it out to be. As pointed out by several posters, Royal Purple and other manufacturers make standard level ZDDP synthetics for flat-tappet engines.

If your engine started smoking after using synthetic, then it is probably worn out and the synthetic oil cleaned out all the sludge that was preventing the blow-by. Just like motor honey seals rings because it is so damn thick, synthetic flows better that conv. oil, so it might get past some weak areas in a worn out engine. That said, I guarantee you that even though it smoked, the bearings loved that new oil.

For the guy that lost oil pressure- that is one of the side effects of synthetic, you have to get used to it. While conventional oil needs that 10-psi per 1,000 RPM pressure, synthetic only needs about half that. It can be unnerving, but it's true. Remember, synthetic oil flows 7 times faster than conventional oil, which means less pressure in the pump, but more fluid passing through it.

 

One of the reasons that older engines might not have luck with synthetics has to do with additive clash. Some of the newer oils do not mix well with older oils or their residuals. You get a reaction that turns the oil as if it were soured milk. One of the places that a good amount of residual will be is in the lifters, not so much the newer rollers. There is a lot of info on the Gibbs site regarding this. I think that it may be a bad thing to just drain your oil out of an engine and put in another chemically different oil. It may also be a bad thing to add an additive to an oil that is not formulated to accept it.
While I am sure that I am not answering your question, I feel that there is no longer a common or stock answer to this question. I think that you need to contact those suppliers makers of these oils and ask them on an individual basis as to the compatibility of their specific products and interaction with other formulas.
Sux but I think it's the only truly accurate thing to do.

 

I like using synthetic up north due to the cold start oil pressure. Your engine can be damage over time due to it recieving little lubrication in the first 5-10 minutes of a cold start in-40. also it does give superior lubrication to older engines. I wasnt, however aware of the zinc issue so this is news. Ill have to start additives in my older engines that are running synthetic, but i wont discard the oil outright.my 2.5 cents

 

Regular oil isn't always cheaper. Manufacturers are making synthetic blends because it is cheaper for them to do that than it is to make "regular" oil meet the same standards.

The synthetic oil used in jet engines is a completely different product than synthetic piston engine oil. It tolerates the temps and conditions present in a jet engine, but isn't really suitable for car engines.

There is no question that synthetic oil offers the potential for improved mileage and in some cases slightly more peak power. Synthetic is better than "regular" at temperature extremes. And while slipperiness isn't a reliable gauge of lubricating capability, synthetic oil is slipperier than "regular' oil. Beyond that there are pluses and minuses, and synthetic isn't necessarily better than "regular" oil in every way. There are situations where "regular" oil is better than synthetic.

While I haven't seen a can of STP in years, if it is still the same product it used to be, it is a poor lubricant. If you are using it and not having problems that's just an indication you aren't very close to the edge.

Glad things worked out ok. Believe it or not, that same thing could have happened with "regular" oil.

 

uhmmm... bullshit.

thank you sir.

Thank you sir....

Standard level ZDDP for flat-tappet engines is above the regular amount in common oils these days. Yes to much is bad, but not enough through the life of the engine is bad to. Common oils don't have enough, common synthetics don't have enough. Get your facts correct...

Some engine with relatively low seat pressures will get by without it, but you are rolling the dice. Once you step up the spring pressure on a flat tappet cam you better have it... or you will regret it. Now if you change your oil at ridiculously low intervals you might survive. But if you go regular intervals, or try and go longer due to the "it's synthetic it'll go a while longer" theory it'll bight you.

 

Back when I first heard of synthetic oils I tried, I think it was Mobil One "Fire and Ice", in my 150000 mile '76 Dodge PU. In less than one week it was out of oil. Never saw a leak anywhere. Went back to dino oil and no more problem. That had to be somewhere around 1980. I was afraid to use it for years till I bought my diesel F350. Previous owner said he has only used synthetic since new. I've since put 60,000 on it with synthetic and at 179,000 miles it uses 1/2 quart in 3500 miles. Go figure