Has anyone successfully switched to low-weight synthetic on a high mileage engine?

Discussion in 'Ask An Owner Operator' started by double yellow, Nov 21, 2014.

  1. double yellow

    double yellow Road Train Member

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    In the 90s I remember switching from conventional Castrol to synthetic Red Line in a 60,000-mile sports car and developing multiple leaks almost immediately. Kevin Rutherford says the new synthetics don't do this anymore, but I'm still leery.

    My series 60 has ~800,000 on an inframe, but uses less than 1 gal in 15,000 miles and doesn't leak 1 drop. Am I crazy to consider switching to synthetic? I'm due for a PM and would like the improved cold cranking & fuel economy offered by a thinner oil.

    Has anyone switched to synthetic on a high mileage engine without developing leaks or increasing oil consumption?
     
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  3. blairandgretchen

    blairandgretchen Road Train Member

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    Thought I heard him say a gallon in 15 k was a prime candidate - and that a gallon every 3,000 is more of a deal breaker.

    I just switched the Chevrolet over to synthetic at 110k, I'm as paranoid as you!
     
  4. Dr_Fandango44

    Dr_Fandango44 Road Train Member

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    Interesting that you bring up this topic as I was talking to a couple of our mechanics at one of our terminals. Some engines are designed to run on this new synthetic stuff but others no. Our company runs mostly Volvos and the guys were telling me that they have had no problems til recently when they decided to switch to the thin weight oil. They've now started to experience blown engines, so you might want to investigate further about the switch. As usual YMMV.
    good luck.
     
  5. mattbnr

    mattbnr Road Train Member

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    Synthetic is a good oil. Just use the same hot weight. If it's 15-40 now use a 10-40 synthetic if you can find one. I'm not sure if a 10-30 synthetic blend would better or not.
     
  6. spyder7723

    spyder7723 Road Train Member

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    The problem is synthetics have a much greater cleaning effect over conventional oils. Even high detergent conventional oils such as rotella will develop sludge buildup under the right conditions. Idling and extended drain schedules are leading factors. Any sludge buildup inside that engine will be broken free, this can plug up the oil ports inside the engine. The rocker arm shafts on series 60s are very susceptible for this. The oil ports that supply the rocker arm bearings are as thin as a sewing needle. I'm not saying don't do it, but if it was me, id pull the valve cover off first to see off you have a lot of sludge on top of that head.
     
  7. Passin Thru

    Passin Thru Road Train Member

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    I wouldn't change. It's about the same price/mi and not really synthetic. Just part. I use Lucas additive and oil samples.
     
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  8. CMFofNC

    CMFofNC Bobtail Member

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    I worked a total of 36 years in the Tobacco Industry, Maintenance, Research & Development, & Maintenance Supervisor. There were a number of company's that switched to synthetics early on and they had machinery that developed leaks. After a number of years the Machinery Manufactures released bulletin's stating that if you decided to switch to Synthetics you would have to change out the oil seals first. The original seals were not compatible with the Synthetic based oils, for those that wished to change all the oil seals a list of compatible part numbers were released.

    Personally I prefer the synthetic based oils and greases as long as it is in late model equipment with compatible oil seals. Never use a synthetic oil during the break-in period, for new or rebuilt engines you need oil with a lot of zinc and other additives so that the cam and lifters will were in properly, be sure to use the recommended break-in oils for the recommended miles or maybe even longer to be sure everything seats in properly.
    Owners manuals should outline the proper break-in procedures for new equipment, personally I run the petroleum based oil for twice the recommended break-in period before changing to synthetic.
    Newer engines have roller lifters and they don't require the zinc for break-in that flat tappets do.

    As far as oil leaks go a thinner oil will leak less than a thicker oil will, the thin oil will run down the inside of the engine faster than the thicker will, the thick runs down slower and crankcase pressures will blow it out every place that has a little wear.

    CMFofNC
     
  9. Cowpie1

    Cowpie1 Road Train Member

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    I have some issues with Lucas, PT. For one, when sent into a oil analysis lab, all that it could be determined was that it was nothing more than a heavy weight (140w or higher) base oil. No additives, nothing. The other, is just the name itself.... Lucas Oil Stabilizer. Much as I try, I can't seem to get my feeble brain around the idea that modern engine oils are unstable. But Lucas sells a lot of it. I just never found a good reason to thicken my oil with it.

    It isn't the synthetic that caused the leaks back in the day. It was the additive package that makes up a large portion of any oil, conventional or synthetic. All synthetics, for some time, have had the proper seal elastomers as part of the add pack, so the leaking game is over. That is unless there is buildup over a bad seal that might be exposed from the cleaning properties of the more advanced add packs in modern synthetics. Can't blame the oil on that. Just bad seals that got exposed.

    I have been running a blend in my Series 60 for some time. I don't use a gallon in 20,000 mile OCI's. Cost is reasonable. I get a Schaeffer 15w40 synthetic blend (75% Group II+ and 25% Group IV PAO) delivered to my front door, for free, at about 18.50 a gallon. It has a -38F pour point and engine starts great on a cold morning, with quick oil flow, even without block heater or oil pan heater plugged in. And they throw in free oil sample kits and free analysis as part of the package. My used oil samples look great over 20,000 mile interval. Mine is a rebuilt 12.7L with 340,000 miles on the rebuild.

    But, this fact remains.... you have gotten good results with what you have been doing, I would be the last to suggest you change anything. I would stick with what has been working for you. Any marketing fluff about increased mpg and such may not ever be realized by switching. And then, it would be barely noticeable. Most times, truth be told, folks will change something or make a modification to get better mpg, and they do, but it has been studied and found that folks sometimes are so intent on the mod or change working, they unconsciously improve how they drive and that is where the real mpg improvement actually came from. With synthetics, they are a better product, but only in the right application and situation. It is not the cure all for what ails folks at the fuel pump. And for engine longevity, I took a Cummins N-14 to 1.4 million (30,000 mile OCI) without ever opening it up for a repair, sold it, and it went right to work for the next user. All on a Kendall 15w40 conventional oil. The oil folks are going to have a hard time convincing me that a higher priced synthetic would have done much better. I opted for the Schaeffer blend I am using now, because of the entire oil package of additives and synthetic blend. It has a high moly content that is an excellent friction reducer. That is a soft metal that offers great boundary protection from metal on metal contact from the engine parts. Along with a very strong level of zinc and a nice dose of Boron. These three compliment each other. And the oil has great cold flow properties. And the oil, along with free oil sampling, makes it good buy. And I don't have to go get it. It is delivered to me free of charge.
     
  10. dannythetrucker

    dannythetrucker Road Train Member

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    Cold cranking ? Does your truck start or doesn't it ? Don't tell me thinner oil is the difference. That's a myth.

    As far as mileage, let's see some data on that too. It takes what 1/2 hour for 15w 40 to reach operating temp ? You gonna seriously tell me that 5w 30 will make significant mileage gains ? I want the protection of 15w40.

    My advice, run Delvac in your Detroit. Rotella in Cummins. Proven. Let Rutherford accumulate some more data before jumping on the bandwagon.
     
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  11. Cowpie1

    Cowpie1 Road Train Member

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    It isn't about "cold cranking", it is about oil flow. An oil with a lower cold flow pour point will flow easier and reach the top of the engine quicker and provide boundary lubrication sooner, thereby reducing the time the top end is without full lubrication. This is not a myth. Set a 5w40 or 10w30 in a -40F freezer along side a 15w40 and see which one pours faster. Even seconds of loss of boundary lubrication can cause unnecessary component wear. The sooner the oil can provide full boundary lubrication the better. This is one of the fortes of synthetic oils and blends, regardless of grade. They flow better and provide quick boundary lubrication at colder temperatures.

    Let's see positive proof in controlled testing that a 30w oil will not protect as well as a 40w oil. You want the protection of a 15w40, will a 5w40 protect as well? And why wouldn't a 10w30 protect as well? There is considerable data available that refutes the 10w30 will not protect as well as a 15w40 in commercial heavy diesel engines. Did you realize that there are large diesel engines, that make the typical 15L engine in a commercial truck look like a portable generator engine, which use a 10w motor oil? This "thicker is better" idea has long outlived it's time. Internal engine component tolerances are considerably tighter than in days gone by. Boundary lubrication is more critical in the newer engines, and the 10w30 oils are proving to be more than up to the challenge. In some cases, out performing standard 15w40 motor oils. Some tolerances are so tight in many modern engines, that until a 15w40 is up to full operating temperature, there is inadequate boundary lubrication occurring. A 10w30 solves many of those problems in tighter tolerance engines.

    And oil shearing, or break down, has been shown to occur less frequently with a 10w30 as opposed to a 15w40. There are fewer viscosity improvers needed in the 10w30 to make the oil perform as a multi grade oil. Shearing of VI is the primary culprit in an oil going out of grade, and modern VG turbos, for one, are brutal to VI's in engine oils. There are some PAO synthetic 10w30's that use no viscosity improvers at all, making them the most shear stable oils available. They are essentially straight 30w oils, but they have the cold flow properties that they qualify as a 10w30. There is not a 15w40 or 5w40 oil on the planet that can avoid using viscosity improvers to make it an effective multi grade oil that meets engine OEM specifications.
     
    Last edited: Nov 21, 2014
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