Synthetic oil ?

[rdmst71]

Time for an oil change and I am thinking about using a synthetic oil this time and not the 5W30 or 10W40 conventional oil that I have  been using in my 1948 Roadmaster.

Anyone had experience using synthetic oil in a Buick straight 8 or any older engine?   This engine does not have hydraulic valve lifters and the speedometer reads a

little over 94000 miles.   I think this is the original mileage.

[DonMicheletti]

Lets see, this engine has run 94,000 miles for nearly 70 years on oil, when it was new, was crap by today's standards. Why waste the money on a synthetic.

Almost anything you can buy today is far superior to what was available 70 years ago.

[smithbrother]

Amen, I guess that goes with the slogan, "IF IT AIN'T BROKE, DON'T FIX IT".

 

Just an old fellows opinion, but I to AIN'T BROKE,

 

Dale in Indy

[Paul Falabella]

Curious why you'd consider switching?

[Matt Harwood]

I am a fan of synthetic oils, but I also think they're overkill on an old car and may lead to different issues, the biggest being that synthetic oils are made of smaller molecules (chains instead of clusters of hydrocarbons, to be specific). As a result of this, they find their way through holes that are too small for conventional oil molecules and leading to the long-standing myth that synthetic oils "cause" leaks. They don't cause them, they just find holes that are already there that regular oils couldn't fit through. So with any old car that uses, say, cork gaskets or porous old castings, you're going to see some additional seepage.

 

Then there's cost. Last night I did an oil change on my late-model, which does require synthetic oil, and it was about $85.00 doing it myself, in the driveway. I believe the big Buicks hold more than 8 quarts and at about $9/quart, well, it's going to add up pretty quickly for you. I think the cost:benefit ratio on a low-revving, low compression, seldom-used, cool-running, non-turbocharged, non-emissionized old car is way out of whack with synthetics. As someone pointed out above, any oil you buy today is better than the best oil in the 1940s.

 

Personally, I run Brad Penn oil in my old cars. It's conventional oil, but it's formulated for use in old cars. That means the right levels of zinc, you can get straight weights, not multi-vis, and after a demonstration of how "sticky" it is from one of their engineers, I became a believer. It, too, is expensive, but I think it's the best choice for any old car.

 

Hope this helps!

[West Peterson]

I agree with Matt. Synthetic is really good for the old car engines, but it definitely finds ways to escape.

[SpecialEducation]

Synthetics are more stable, especially in extreme temps, but I don't know that I'd use 5W30 in anything that wasn't designed for it.  Unless you've got a fresh build with much tighter tolerances than the original specs, 5W30 is awful thin.  Unless you are driving it on really cold days, 94,000 miles is a time where you might consider going to a slightly heaver oil, not a lighter one.

 

I've caught flack for saying this before, but a significant change like this can dislodge deposits and make things worse.  With no more miles on it than you seem to be accumulating, one oil change a year using a good quality conventional is probably sufficient.  To do a changeover to Synthetic, you are probably looking at 2 or 3 oil & filter changes in a fairly short time, and in the end I don't think you are going to see much advantage for your investment.

 

It's not that you can't or shouldn't go synthetic on an older engine, it's just that the costs seriously outweigh the benefits.  If you were putting 20k/year on the clock, it would be a different story.

[avgwarhawk]

Stick with the dyno oil.  Less expensive and a better product from days gone by.  Your Buick has over 90k on the ticker and working fine.  I so no reason to change.  Furthermore, the money you save buying conventional oil is at least a 6 pack or 2 of beer in savings.   

Edited March 24, 2016 by avgwarhawk (see edit history)

[Paul Falabella]

31 minutes ago, SpecialEducation said:

I've caught flack for saying this before, but a significant change like this can dislodge deposits and make things worse.  With no more miles on it than you seem to be accumulating, one oil change a year using a good quality conventional is probably sufficient.  To do a changeover to Synthetic, you are probably looking at 2 or 3 oil & filter changes in a fairly short time, and in the end I don't think you are going to see much advantage for your investment.

I agree with this. In the early 80's I bought a 41 Super. Without thinking, the first oil change I used detergent oil. The formerly quiet engine developed a piston slap. Very expensive oil change.

[Guest 54fins]

I get a chuckle out of the "smaller molecules" you hear about synthetics. Not necessarily true and not really the issue. I use all synthetic in newer low mileage cars. The reason you don't want to use them in older steel engines is they can eat seals and they will clean out old deposits. If they start a leak it was already a problem that may have been plugged with sludge but sludge is bad for any engine. The real reason you don't want to use modern synthetic fluids is they can be aggressive on old seals but really because its not worth the money. Modern additives eat the sludge too.

The issue is that all the fluids should have been serviced at least every other year and there is a high probability that didn't happen the older a car is. Synthetics can be more stable but when they go acidic they can even be worse than mineral oil. Its simply a waste of money as you must change all your fluids every year even if you don't drive it much. Mineral oil is a lot cheaper and there are no questions of seal compatibility. Also use the green stuff in your radiator and flush it every year. We are dealing with rubber seals and steel and there just isn't a good reason to go synthetic on vintage cars.

Now, the sludge is a different subject. No sludge is OK and sooner or later it will break loose. Old cars almost always sat for several years with old fluids and have old sludge from crappy 60's oils. You can leave it alone, but it destroys the additive package in your oil. Once you put in new oil and get it good and hot its simply a matter of time before it wipes a bearing or a valve. Motors are not easy to desludge but its got to get done if yo want a reliable motor. And you can bet the diff and the tranny have not been serviced. Save the synthetics for 90's and up cars that you drive a lot.

 

[rdmst71]

I appreciate all of your input, considering this information and from what I have learned doing a little research on line, I see no real benefits for me in changing to a synthetic oil for this engine.

I would be spending more money than I need to ( engine requires 7 quarts of oil ) and I may end up creating problems that I don't have now.  

[avgwarhawk]

[NTX5467]

The "smaller molecule" can work with certain brands of "dino" oil, too.  A friend of mine cussed Castrol GTX as it "leaked", but when he went to Pennzoil, the leak stopped.  Nothing to do with an area "hidden" by sludge, just that the Castrol got into places (and through the rubber/cork valve cover gaskets easier than the Pennzoil did.  I had never had that issue with Castrol GTX in my cars, back then, but my friend did.  When I mentioned this to my machine shop operative, who bought oil for his personal pickup by "what was on sale when he bought it", he mentioned that some brands would seep through the valve cover gaskets "better" than other brands did.  So not specifically "smaller molecules", but lighter fractions of the total oil product (as all that discussion was on normal "dino" oil).

 

Conventional wisdom might dictate that 5W or 10W-30 oil is too light for an engine designed to use straight weight 20 or 30 oil.  If you shake a quart of 10W-30 oil and then 30 oil, the multi-weight will feel and slosh "lighter" and easier than the straight-weight oil will.  The reason that so many newer vehicles use multi-weight oil is that it will get into circulation  quicker than the straight-weight oil will . . . when the engine is started, whether a "first start" or a "re-start" during the day.  When the then-new "0W" multi-weights first came out, it was claimed that the oil was fully-circulated about 30+% quicker than with a 10W-30 motor oil.  More oil in more places, sooner, can mean less engine wear, regardless of whatever model year the engine might be.  Should oil consumption increase noticeably, then some adjustments in oil viscosity might be needed.

 

Remember, too, that many older engines spec'd "20W-20" oils for certain ambient temperature ranges, even with the "looser" internal specs of the older engines.  It was more of an oil flow issue in the colder weather than anything else, though, as "30" was spec'd for warmer and hot ambient temperatures.

 

I strongly concur about modern oils being phenomenally better than ANY oil of the 1940s, or even 1970s.  Issues could be, though, zddp levels, which can be addressed in several manners (either specific oils with known higher levels of zddp or oil additives from camshaft manufacturers or possibly the new Rislone zddp oil additive).

 

Perhaps a synthetic-blend oil might satisfy your desire for "something better"?

 

NTX5467

[Paul Falabella]

On March 24, 2016 at 1:12 PM, 54fins said:

Now, the sludge is a different subject. No sludge is OK and sooner or later it will break loose. Old cars almost always sat for several years with old fluids and have old sludge from crappy 60's oils.

Drop the pan. This is what I found when I dropped mine. Didn't have an oil pressure problem either but the pickup was pretty clogged too. And it gives you a chance to make it nice and pretty !

[DonMicheletti]

What you found is pretty typical on an old engine, and a potential problem waiting to happen.

[Lapham3]

That's actually less than I've found upon tear down on most. The paint scrapper is usually required

[Paul Falabella]

There was actually a little twig in there if you look closely!

Edited March 27, 2016 by Paul Falabella (see edit history)

[gdmn852]

 Hello, Penn-Brad makes a straight 30 wt. oil that is high in zinc content ,they call it a break in oil but I use it in my 1949 Super. Its also made for older engines with flat tappets.Some of their multi weights are semi synthetic but check the website at www. pennbrad for more info.Hope this helps   

[gdmn852]

Wrong website sorry should be http://www.penngrade.com they changed the website not as helpful as before.

[NTX5467]

Saw the twig!!

 

One thing about some synthetic oils, some more than others, is that an "ester-based" oil will liquefy sludge and help remove it.  Esters are those sweet-smelling chemicals which we learned about in high school chemistry class. 

 

Back in the 1990s, Chevy/GM put out a TSB on "engine knock" upon cold starts.  The TSB stated to do ONE oil change with Mobil 1 and then return to your normal oil.  At the time, I thought "What???!!  Why not just keep on using Mobil 1?"  Later, in some non-related (to the TSB) posts on www.bobistheoilguy.com, it was mentioned that ester-based oils would liquefy and remove sludge from engine internals.  That's when I realized what was REALLY happening with the Chevy small block oiling system parts, back then . . . somewhat similar to a high-mileage Buick 3.8L V-6, I suspect.

 

Therefore, the one oil change with Mobil 1 was to clean out the internal oil passageways of the block and crankshaft.  In another post on the oil website, I saw signals that Mobil 1 was, indeed, ester-based synthetic motor oil.  BUT, when I was at a car expo and Motul had a booth there, I discussed the ester-based situation with the rep.  The rep opened a bottle of oil and a very similar smell to that old chemistry class "ester" smell was there, significantly so.  Be that as it  may.

 

Nice paint on the oil pan, Paul!

 

NTX5467

[Shakadula]

Don't know if this makes sense but I switched to syn oil and my rope seals leaked like crazy. These new rope seals are not like the seals of old. Anyway I put the suggested oil back and and the seals still leaked. It wasn't until i replaced the new rope seals with newer rope seals did the leaks stop. And I do mean front and rear seals. 

 

So I blame the rope seals for not being able to use syn oil. An observation and not based on any facts. 

[buick man]

On March 24, 2016 at 6:15 AM, West Peterson said:

I agree with Matt. Synthetic is really good for the old car engines, but it definitely finds ways to escape.

…. and why is that ? Any specific details you would car to share with us that synthetic oil is good for older engines that were designed back in the middle of the last century ?