Synthetic oil: Worth it? Oil-change frequency?

Discussion in '4-Stroke Engines' started by mystic-chris, Apr 27, 2011.

  1. mystic-chris

    mystic-chris New Member

    Very shortly, I'm going to be firing up a brand new 49cc Hua Sheng F142 4-stroke engine on a new MB build. With the small crankcase on such an engine, the extra cost of synthetic oil really isn't a factor for me. Anybody have any experience or thoughts on using synthetic oil? Do you have a specific brand/formulation that you like? Is it OK to use synthetic for the break-in period? And how often would you change your synthetic oil?

    Back to the break-in period question: I've heard a variety of suggestions as far as how one should ride during new engine break-in (varied RPMs, steady RPMs, etc) and mileage needed to adequately break in the engine. Any thoughts on this?

    Thanks MBers,


  2. machiasmort

    machiasmort Active Member

    Synthetic is worth it! Break your motor in on Dino oil only! It will help the rings seat and then you should make the switch to synthetic. I run it in my HT 2 stroke and have almost 2000 miles on it!

    Varied RPMs and speeds are the best, don't ring it out! You don't want to horse on it! Resist the temptation, it's worth it in the long run! Length of break in is up for debate.
  3. darwin

    darwin Well-Known Member

    Change the oil when it gets dirty, synthetics are proven to reduce wear vs conventional oils.
  4. spad4me

    spad4me Member

    The more frequent and regular oil changes are better overall.
    If a cheaper oil lets you change it every 1000 miles go for it.
    In my opinion the finest motor oil for a four stroke is royal purple.

    The oil that you can afford to change often is the best.
  5. Skyliner70cc

    Skyliner70cc Active Member

    'dirty'...visual inspection is not an accurate method to determine when to replace oil. oil contains detergents and suspension agents to keep contaminates in suspension and the oil can still have plenty of life left when it is visually discolored.

    For small engines without a oil filter using synthetic, an oil change every 50 hours is reasonable not to exceed one year...which ever comes first when using synthetics. However, first oil change on a new engine should be done sometime between 5-10 hours.

    Because these engines are aircooled with no oil filter, I use nothing but HDEO in them. They contain more additives and have a longer life than regular oils. My favorite for year round use is mobil 1 TDT 5W-40 but any synthetic HDEO is ok as long as they are not ESP oil that contain very little ZDDP and have low TBN numbers.
    Last edited: Apr 27, 2011
  6. darwin

    darwin Well-Known Member

    On cars with an odometer I go 3 to 5k before changing the oil, on these mabs I cannot keep up with the hours or milage. I put clear oil in and when its starts to darken I change it. The black particles in the oil are abrasive so in my opinion its time to change it. Heck 1qt is 4 oil changes maybe 5 on my r/s 35cc.
  7. Skyliner70cc

    Skyliner70cc Active Member

    please go to and read their forum's on a regular basis. i used to be one of those guys who wasted natural resources with 3-5k oil changes. instead of relying on color, i now use oil analysis labs in all of my vehicles and in one vehicle i change oil every 10,000 miles and on the other every 15k miles. both vehicle's oil analsyis measures insolubles in oil, wear metals, residual additives, visocity and other parameters. Before you say anything, the first vehicle's recommended oil change interval is 10,000 miles and the second vehicle's oci is 12,500 miles.
  8. darwin

    darwin Well-Known Member

    Old Bob seems like a book smart kinda guy, whats his experience in tearing down motors to see what damage is done by oil sludge and carbon buildup? Is it 1 motor, 2 maybe, or none? How many resources are you using up in each engine oil analysis? I'll rely on my half century of experience and you can trust Bob who has never tore a motor apart and only reads books. Every one has an opinion on oil and no 2 are the same.
  9. Old Bob

    Old Bob Member

    I've been working on the Honda mini four strokes since they came out, I've taken apart more engines than any 5 of you of guys combined.
  10. darwin

    darwin Well-Known Member

  11. Skyliner70cc

    Skyliner70cc Active Member

    Old bob is a forum filled with great members like this one. Bob Is The Oil Guy (BITOG) began in May 2002 with a handful of participants and now the oil forums have over 34,000 registered members. Members include well-respected tribologists-its a big word so u may way to look it up-, chemists, and oil analysis professionals who regularly participate and contribute their knowledge and expertise. The website is about educating you so you can make informed decisions about the life blood of your engine: motor oil.

    I recall following an oil longevity study that began in 2002. It compared several synthetic oil changes against each other and oil samples were pulled every 1000 miles to see how far the oil could go before it needed replacement. Google paradise garage oilstudy to read up on it. If you have any intellectual curiosity you'll find yourself intrigued at the least.

    here is a little snippit from that oil study

    'To date we have completed our tests of Mobil 1 and Amsoil. Mobil 1 held on for 18,000 miles, and didn't need its first oil filter until 12,000 miles. For all the details, visit our Mobil 1 Test Results page. Amsoil was time-limited to 14,000 miles (its year ran out), but it made it the whole way without a replacement filter. It's not a total success story, though, as it had some trouble with its viscosity.'

    Another observation from the oil study was that each time that the oil was changed, there occurred a spike/increase in the amount of engine wear metals in the oil cample pulled at the next 1000 mile oil sample. This effect has also been observed in 100's of oil sample analysis posted on bobistheforum guy forum leading some to speculate that too frequent oil changes can increase engine wear and that may be due to the new additives in fresh oil needing time to be 'activated' by heat and pressure

    I forgot where i read it and wish i kept the link to the story about how many billions of dollars oil company's make by people changing their oil by a 100 miles sooner than called for. The 3k oil change interval spouted by advertises for iffy lube and other shops is just for greed and profit.

    Yes, you are correct...I have never had to pull a sludged engine apart and rebuild it..because the info I gained from that website allowed me to become a better educated consumer and user of oil products just like the knowledge gained from this website has allowed me to do the same as a motorized bike user. I've been using using extended oil change intervals for almost 10 years now and never had an engine issue. European's have been ahead of the game with extended ocis and 2 of my engines are european made. the manufacturer of each engine and vehicle manufacturer state that oil change intervals are as follows; 1. for my 06 jeep liberty CRD 2.8 liter vm motori italian turbo charged engine 7,500 mile oil change interval for severe service and 10,000 mile oci for non-severe service. my 07 jeep grand cherokee with the mercedes 3.0 liter engine states that the severe service oil change interval is 8750 miles and non severe service oil change interval is 12,000 miles using low sap/esp oils. neither engine's turbo has failed yet and when i pulled the valve head assembly to replace a leaking valve cover gasket on my liberty last year....she was spotless inside with no varnish or sludge.
    Last edited: Apr 29, 2011
  12. darwin

    darwin Well-Known Member

    Some times its hard to teach an old dog new tricks. Some times with me my choice for changing oil depends on the funds availability situation. If things are tight I just use what ever conventional oil is on sale, with that oil change 3k it gets changed. If I use synthetic blend 5k, full synthetic 7.5k and cost is a factor. I just cannot go 10k to 12k in between oil changes on a car with out feeling guilty that I'm some how abusing that motor.
  13. Skyliner70cc

    Skyliner70cc Active Member

    I used to feel the same way but technology with engine oils have progressed a long way and with a great syntethic oil (a real one, not the severely hydrocracked Group III oils) that you aren't abusing your engine in anyway. I used to fly Chinook helicopters and oil samples were pulled every 25 hours of flight time and oil in those 4500 shp turbine engines was hardly ever changed.

    The first time I did a 10,000 mile oil change interval, I sent an oil sample to Blackstone labs. The results showed great wear rates and that my oil still have another 5000 miles of life in it. Insolubles (dirt in oil) was way below max and soot loading was also great (less than 1 percent). TBN (total base number) was a 9 (a 1 value means oil is done) etc...etc...
  14. Skyliner70cc

    Skyliner70cc Active Member

    Here is a UOA (used oil analysis) of a 10k oil change interval

    150k on engine, 10k on this oil. Mobil1 0w40 and Mahle filter. Blackstone Labs.

    IRON 19
    COPPER 3
    LEAD 1
    TIN 0
    NICKEL 0
    SILVER 0
    BORON 76
    SODIUM 8
    CALCIUM 2860
    ZINC 989
    BARIUM 0
    cSt Viscosity @ 100°C: 64.7
    SUS Viscosity @ 210°F: 11.5
    Flashpoint in °F: 375
    Fuel %: TR
    Antifreeze %: 0
    Water %: 0
    Insolubles %: TR

    Here is another 10,000 mile oil change interval
    Last edited by a moderator: Dec 18, 2015
  15. machiasmort

    machiasmort Active Member

    Filter size is a major factor there, don't you think? You might get a good filter or bad one depending how the glue is comming out of the gun that day at the factory!
  16. spad4me

    spad4me Member

    Hey old bob some of us have been around gasoline engines for a while.
    I made a mistake one year and went to work for Sears as a small engine mechanic .
    Lawn mowers and such stuff.
    My area was an entire state by myself.

    I burned out quick with that overload.
    I must have worked on at least one thousand 4 stroke motors.

    I would rather use Wallmart catch of the day oil and be able to afford to change the oil every thousand miles.
    If I can afford it I use royal purple and still change it at 1000 miles.
    Wallmart oil $8.00 a gallon.
    Royal Purple $8.00 a quart.
    Change the oil often.
    Last edited: May 2, 2011
  17. Old Bob

    Old Bob Member

    I'm a firm beleiver in the oil analysis, but these small engines don't have filters on them, not changing the oil leaves particulates in engine.Frequent changes does help the service life.
  18. Silvaire

    Silvaire Member

    Oil price is irrelevant with little 4 stroke engines. With either a Subaru EH 035 or a Honda GX35, you get over NINE 100cc oil changes per quart.

    Of course using an appropriate oil is essential, but assuming that you are, the frequency of oil changes becomes the important factor.

    I don't think using synthetic in these little 4 storks is a bad idea. Going up long hills at full power on a hot day is not an uncommon occurrence with a motorized bicycle, and this can cause them to severely overheat. Synthetic oils generally maintain their lubrication properties to a higher temperature than mineral type oils, and they also go longer before they begin to break down.
  19. Old Bob

    Old Bob Member

    Dyno testing Synth hasn't shown any significant difference in wear,operating temp or power out put.
  20. loquin

    loquin Active Member

    However, standard oil (virtually ALL oil, standard or synthetic, is 'dino') has a blend of shorter and longer hydrocarbon molecule chains which 'average' out to the viscosity on the bottle, whereas synthetic oil has had its hydrocarbon chains split, then recombined, to create an oil where almost all the hydrocarbon chains are the same length.

    This difference won't matter with new oil, but, as the engine runs for a while, some of the oil evaporates. In synthetic oil, where all the molecules are about the same length (and weight,) it really doesn't matter, since what is left behind is essentially the same as what evaporated. BUT, with standard oil, since it has a blend of shorter and longer molecule chains, There IS a difference in what is left... Since the shorter chains tend to evaporate first (they're lighter,) it leaves behind a 'thicker' oil with a higher viscosity, as time goes by. The thicker, higher viscosity oil doesn't lubricate as well at engine startup.

    You would need to run tests on many engines for a hundred thousand miles or more, to be able to tell whether there is a significant difference in wear between standard and synthetic oils. If you keep up on your oil changes, changing standard oil regularly, when needed, you wouldn't see a significant difference in wear/power/mileage for a long time.

    Where synthetic oil really helps is in high temperature regions, and in other very hard usage applications, where standard oil tends to change viscosity much more quickly than synthetic.
    Last edited: May 3, 2011