Synthetic Oil in Older Engines (Tested)

Found this on YouTube. Seems like a comprehensive and compelling dispute of the popular notion that you can’t use modern synthetic oil in older diesel engines.

I have been using synthetic oil on my 36 year-old Lehmans for five years. No leaks.

Heck my Lehman leaks oil even after I have taken out the oil for a change...

Greetings,
Mr. A. Thanks. I've watched a number of this fellow's videos and quite enjoy them. As he said, his test had a data base of one so synthetic seems to work for him.

We run Lehman 120's and I've always used Rotella (T-?). I really can't see the advantage(s) of switching to synthetic given our engines do not seem to be running in "extreme" conditions and the oil is changed every 100 hrs. Not worried about leakage as Mr. ps notes, they DO leak/seep.

I suppose the bottom line is; is a recreational boater getting his/her money's worth with the extra cost for the synthetic? Can one extend oil changes to say...200hrs. or 300hrs? What about the injector pump? Any potential damage if one uses synthetic?

If you aren't planning to run long changes and the engines don't run super high oil temps or have other conditions known for being hard on oil, then synth probably isn't worth it.

But if you're going to do oil analysis to see how long you can run, a good synth will usually last longer. And if you have engines that are hard on oil, it can make a bigger difference.

The other factor is cold weather. Personally, my gas engines get Rotella 15W-40 (non synth), as they don't get started in particularly cold weather (under 50* F is very rare), they're not hard on oil and I usually don't put enough hours on in a season to benefit from synth. However, if I were boating in the winter and starting them in colder conditions regularly, I'd go to a synth 5W-40 for better cold start flow (without having to sacrifice hot viscosity to get it).

Airstream345 said:

Found this on YouTube. Seems like a comprehensive and compelling dispute of the popular notion that you can’t use modern synthetic oil in older diesel engines.

Click to expand...

I've gone back and forth from synthetic to dino oil and back on various engines for various reasons and have never had a problem. (or a sudden oil leak)

IMO the biggest benefit of synthetic is you can theoretically (at least) run it longer and its better at the performance extremes. Not an issue in my Lehmans so I run 15-40 and don't worry about it.

Ken

Take a look at the Cox Eng Article on Oil for marine applications.
https://dkloeber.wixsite.com/bacchus/links
It's one of the few I've seen that specifically address marine diesels vs OTR applications.
Many mfg caution that change intervals should NOT be extended with Syn oils.

Bacchus said:

Take a look at the Cox Eng Article on Oil for marine applications.
https://dkloeber.wixsite.com/bacchus/links
It's one of the few I've seen that specifically address marine diesels vs OTR applications.
Many mfg caution that change intervals should NOT be extended with Syn oils.

Click to expand...

Blindly extending change intervals with any oil carries some risk, so of course they warn against it. But it's possible to do used oil analysis to determine how used up the oil is and pick an appropriate change interval from there.

rslifkin said:

Blindly extending change intervals with any oil carries some risk, so of course they warn against it. But it's possible to do used oil analysis to determine how used up the oil is and pick an appropriate change interval from there.

Click to expand...

Good point however the same holds true for dyno oils that will frequently test OK at recommended interval.
I guess the break even point depends on how long an extension one is comfortable with?

Bacchus said:

Good point however the same holds true for dyno oils that will frequently test OK at recommended interval.
I guess the break even point depends on how long an extension one is comfortable with?

Click to expand...

Pretty much. And how much benefit you'll see from synthetic will depend on your engines as well. Some are just harder on oil than others and correspondingly see better oil life with better oil, while some are easy on oil and can run pretty long intervals on just about anything.

RT Firefly said:

Greetings,
Mr. A. Thanks. I've watched a number of this fellow's videos and quite enjoy them. As he said, his test had a data base of one so synthetic seems to work for him.

We run Lehman 120's and I've always used Rotella (T-?). I really can't see the advantage(s) of switching to synthetic given our engines do not seem to be running in "extreme" conditions and the oil is changed every 100 hrs. Not worried about leakage as Mr. ps notes, they DO leak/seep.

I suppose the bottom line is; is a recreational boater getting his/her money's worth with the extra cost for the synthetic? Can one extend oil changes to say...200hrs. or 300hrs? What about the injector pump? Any potential damage if one uses synthetic?

Click to expand...

As Mr RTF pointed out, one question to ask yourself is what added value do you expect from using synthetic oil and does it worth it?
My old venerable engine is running fine with standard old heavy duty sae 30 oil use that cost at most 20$ a gallon, would I get any benefit to use synthetic oil, really not sure about that.

L

I would change the oil each year anyway so no way I would pay the extra to use synthetic oil. I just did a quick check on Amazon and synthetic Rotella is about $63 per gallon. Regular Rotella is $16. So for 4.5 gallons that is an extra 211 per engine, not worth it. Maybe if I was doing 1000 hours per year.

Airstream345 said:

.. notion that you can’t use modern synthetic oil in older diesel engines...

Click to expand...

There are lots of things you can do but the real question is,"should you?" or "is there a benefit in doing it".

Our sump holds 10 gallons.
That'd make a semi synthetic change near $400 vs $200, ($160 on sale) for Castrol RX which is the oil the Cummins and Gardner spanners in these parts suggest.

Comodave said:

I would change the oil each year anyway so no way I would pay the extra to use synthetic oil. I just did a quick check on Amazon and synthetic Rotella is about $63 per gallon. Regular Rotella is $16. So for 4.5 gallons that is an extra 211 per engine, not worth it. Maybe if I was doing 1000 hours per year.

Click to expand...

$63 per gallon seemed a bit much to me. A quick googly and I found both Walmart and a local Advance Auto Parts selling T6 for $20. Compared to $14 for T4, extending a 100 hour drain interval to just 150 hours reaches the break even point. Any more than 150 and you are saving money.

The big truck folks like syn s the extended run time allows fewer expensive oil filters to be needed , and properly disposed of.

Most OTR trucks and RV's use Dino and most I think use Rotella at $12 a gal from Walmart


If you add the cost and time to test syn it's is questionable ROI





In gas powered cars that drive over 10K it makes more sense to go Mobil One


changing at 10-12,000 rather than 3-5,000 on Dino

Interesting thread. I watched a few videos from same person. Seems straight-up. He did this one on Engine Restorer to boost compression. Seems to work on his old tractor.

https://youtu.be/Hr8jIwVyIFE

Our boat has become pretty much a dock condo in recent years. I had been leaving the dino oil in the crank case over one winter. Last Spring I switched to Rotellla T6 synthetic because I believe it is the perfect solution for extended "down" periods. Judging from the look of the oil after one season, I might go for two winter storage periods (I'll do an oil analysis before launch this Spring. If I'm comfortable with two storage seasons...I'm making money over dino oil. Further, I swear the engines are running more cleanly with the synthetic. I'm sold on the stuff. $4 a gallon difference...please. T-6 is going in my E-type Jaguar at the next change.

Greetings,
Mr. mv. "...Seems to work on his old tractor."

My first car was a 1959 VW beetle I bought for $50. I had to spend ANOTHER $50 putting on a new muffler complete with resonator tail pipes. At some point I removed the resonators and installed...gasp! straight pipes (1 1/4" in diameter and about 10" long. The engine sounded "throatier" and I swear the car was a LOT faster. (It wasn't, just louder).

My point is the power of suggestion works. NOT saying the synthetic is the same as the dino and it may be better but for my use, it just isn't worth the extra expense.

Rufus said:

Our boat has become pretty much a dock condo in recent years. I had been leaving the dino oil in the crank case over one winter. Last Spring I switched to Rotellla T6 synthetic because I believe it is the perfect solution for extended "down" periods. Judging from the look of the oil after one season, I might go for two winter storage periods (I'll do an oil analysis before launch this Spring. If I'm comfortable with two storage seasons...I'm making money over dino oil. Further, I swear the engines are running more cleanly with the synthetic. I'm sold on the stuff. $4 a gallon difference...please. T-6 is going in my E-type Jaguar at the next change.

Click to expand...

Not sure I understand what is expected from synthetic vs regular oil if the boat is in storage and the engine not ran??? Oil sits in the pan so what’s the difference?

L

Some of the literature says the synthetic produces and retains less of the potentially damaging pollutants than dino. It sure looks it when I look at the dip stick.

catalinajack said:

A quick googly and I found both Walmart and a local Advance Auto Parts selling T6 for $20.

Click to expand...

I can confirm about the same price in the store (Walmart); $20 and change/gallon. I just bought 4 gallons of T6, 5W-40 for my F-250. 15W-40 is the same.

I have been using synthetics for decades in my truck, which has an International engine, and my JD tractor, which has a Yanmar engine.

The truck oil is supposed to be changed every 5,000 miles. I change at 15,000ish. Friday I changed at 16,000ish. I get a UOA done and last years test said to try 17,000 miles but the weather was nice and I had time to get some chores done so the oil got changed "early." UOA over the decades has said I have been throwing away good oil even with the high miles/hours on the oil. The worst the oil has even been was during a time where I was getting stuck in bad stop and go traffic. Fuel was in the oil from the extending idling BUT it was still within spec.

Why do I use synthetics? It saves me time and money. I get slightly better MPG, when it gets cold I don't have to hook up an engine block heater which really drives up my power bill even using a timer, and I only change the oil and filter once a year instead of three times.

With UOA I know how the engine is wearing.

Is it worth it on a boat?

If you use JD synthetic in a JD engine, you can increase the oil change hours to up to 500 hours instead of say 250. That might be worth it for some and not for others.

Later,
Dan

It may not be a question of “is synthetic oil good in old engines” but what is it about synthetic oil that is questionable?

With that in mind if an additive was a problem one would have problems w some syn oil and not other brands.
Also syn oil comes in a fairly wide variety of base stocks. So if there’s a problem it may be due to a specific base stock.

What caused big problems in the 50’s was much higher levels of detergents. An old car nearing the end of it’s life with the newer high detergent oil very often had a big problem w sludge deposited over many years loosened up by detergents. “Gaps” that were filled w old sludge would become gaps and rods would rattle and where sludge was performing the job of oil seals the engine would leak large amounts of oil. These engines would self destruct rather quickly.
Some people thought it was the MV (multi-vis) element of the new oils that caused the problems.

Oil leaking problems were a big problem when syn oil first came out significantly but this was caused be the tendency for syn oil to shrink oil seals. Correct me if I’m wrong but I believe they put an additive in the oil that swelled oil seals. And if they put in the ideal amount the seals stabilized and the leaking problems stopped. But if they fluck up and put the wrong additive in or the wrong amount the seals could shrink up. It could happen but I don’t know if it ever does.

Anyway the problems of switching to syn in an old engine could result from additives and it could have nothing to do w the syn base stock.

All my life I’ve heard mechanics say not to change the kind of oil you use in any engine. Long before syn oils came out. And syn oils came out via the US Army needing to start equipment like trucks and tanks in very cold weather. Our boat engines never get below 40 degrees or so and hence have no clold weather problems at all. I spent 8 (or so) years in Alaska, used Chevron DELO 30wt oil (and still do) and never had even a hint of slower cranking when starting.

As I’ve said before syn oil has some advantages but I consider those advantages to be fly stuff. Also I can walk up in any SE Alaskan town and get more new oil.