Edmunds Answers



  • texases 05/07/10 1:51 pm PST

    As long as you follow the miles/months/grade requirements in your owner's manual there's no harm changing back and forth. There's certainly nothing wrong with using synthetic oil.

  • zaken1 05/07/10 3:06 pm PST

    There are some people who believe that there is no harm in switching back and forth from conventional to synthetic oil. I expect most of them got that information from reading articles by synthetic oil manufacturers. But some of us have had direct experience with this issue, and have in the process learned very expensive lessons about not trusting the word of a company which has a vested interest in maximizing the sales of their products, and is determined to not raise public concern about a very real issue which could impact their profits.

    I have personally witnessed perfectly good engines losing their ring seal and becoming severe oil burners after switching from synthetic oil back to conventional oil. And these experiences have taught me to be EXTREMELY cautious about such changes. It seem that the effect is caused by the differences in additive chemistry between the two oil types. Mobil 1 is the safest oil to switch back to conventional oil; because its synthesized petroleum chemistry is very similar to that of conventional oil. But the ester based synthetics (used in practically every brand except Mobil 1) are very different than the chemicals in conventional oil; and THOSE are the ones which can mess up the ring seal if conventional oil is ever used again in those motors. It is these same differences between the viscosity and lubricating characteristics of ester based synthetics and conventional oils which has led some car manufacturers to prohibit the use of synthetic oil in their motors. Saabs used to have timing chain failures when ester based synthetics were used in their motors; because the synthetic oil did not cling to the chain. But other engine designs did not have this problem.

    Since one Honda tech told you that synthetic oil was good in your Honda motor; while another Honda tech later said it wasn't recommended in that motor; the first thing you need to do is to find out which tech was wrong. One way you could do this would be to contact those two techs, and ask them what the specific source of their information is (this would be a good way to rule out someone who was using hearsay or their personal opinion in place of company policy). Another way would be to contact Honda's regional customer service office and ask them whether the manufacturer has issued any service advisories about the use of synthetic oil in your vehicle year and model. The third way would be to locate the Honda Technical Service Rep for your area, and ask them whether they have any specific information about this issue.

    Beyond that; if you have been using Mobil 1 in your motor, I would not worry about switching back to conventional oil. But if you have been using another brand; I would not switch back, unless you have a very good reason to do so. It would also be meaningful if the person (or dealership) who unilaterally switched your motor back to conventional oil was confident enough in the appropriateness of their decision that they agreed in writing to take full responsibilty for the possible engine damage which could result.

  • wurkfur 05/07/10 3:30 pm PST

    Synthetic not recommended?

    That's one of the most stupid things I've heard. Today's conventional oil continue to march towards becoming more like a full bodied synthetic every day. Soon we will migrate from the "GF-4" to "GF-5" standard and from the "SM" to "SN" standard. These newer standards set the performance requirements for every oil on the market. Some of the newer "SN" requirements demand better performance for usage in turbocharged engines. This goes for synthetic and conventional alike.

    That said, feel free to use a synthetic if you like. You can more easily go longer between drains without worry, not have to worry about severe conditions as much, have noticably better gas mileage in colder climates, and protect marginally better.

    The reason some people have issues after using conventional is because the synthetic cleans out all the garbage left in the engine from using older conventional oils. The same engine would be near spotless if synthetic were used from the beginning. Given the low mileage you have and the fact that Honda K-Series engines are fairly easy on oil, you should have any "garbage" so to speak.

    As far as the post above me is concerned, he has no clue what he is talking about with regard to the formulations of Mobil 1 and others. I'll say that much. They have different formulations for EVERY single grade. Some hydrocracked, PAO, Ester, and otherwise.

    Bottom line, on newer cars or cars that have been properly maintained, switching shouldn't be an issue.

  • texases 05/07/10 4:40 pm PST

    Zaken, this is the first I've heard of engine damage from switching. The oil and other forums with folk's experience with switching typically indicate they've had no problems. Occasionally folks will switch from synthetic to regular to reduce seal leakage. No mention of engine wear problems. When did this occur?

  • zaken1 05/07/10 6:02 pm PST

    Texases; here is the response I posted to another question about a vehicle which began consuming oil after switching oil types, which contains the specifics about my client (and friend's) 1982 Toyota Cressida's engine destruction in 1997.

    If you changed to a different brand; this may have caused the problem (depending on what the two brands were). Some oil companies claim their oil is compatible with any other oils; and some people on this site buy that sugary, oversimplified PR. But there are many people who have experienced very much the opposite: I am one of those people. I once bought a Dodge V-8 which was in very good condition, and had previously been run on only Shell oil. Shell oil is unique in that they use alkaline additives in it; with the intention of counteracting acid formation created by cold running. I know of no other oil manufacturer which uses alkaline additives in their oil. Since I go to great lengths to not start my engine without driving it far enough to fully warm up and boil off the condensed moisture; the idea of alkaline additives has no value to me. So I promptly switched the car to Union 76 oil; which was my regular oil at that time. And during the next 60 days; the engine rapidly lost compression and power, and soon degraded to the point where I had to have the piston rings replaced. The engine showed no signs of a compression problem before I changed oil brands; and I did not abuse or mistreat it at all.

    A very similar experience happened to a good friend, who is a physician; and who had been using Castrol Syntec full synthetic oil for years in his Toyota Cressida with great success. For some reason, he decided that it was extravagant to pay the cost of synthetic oil (on a doctor's income); so he switched back to Castrol GTX regular oil. And the Cressida soon began consuming massive quantities of oil; and putting so much blue smoke out the tailpipe that my friend said he could not drive it anymore in good conscience. That was the end of his Cressida.

    I have a now out of print book on engine tuning for performance; which stated that many professional engine builders will go to great lengths to NEVER allow a different oil brand to be put into their engine. This is the result of repeated experience in which engines were ruined from the chemical reaction between different oil formulations. Sometimes adding even less than a quart of a different oil brand has been enough to ruin a perfectly good motor.

    In over 40 years of tuning cars for a living; I repeatedly found that some people's cars lasted longer, and consistently ran better than other supposedly identical cars of the same make and model. So I began collecting information about fuel and oil usage in my client's cars. And I soon found out that those cars which ran so much better than average were inevitably the ones which always used the same brand of oil. It didn't seem to matter so much which brand it was; the main thing was that the oil was always changed at the same gas station (this was before the days of quick oil change places). And this, by default, meant that the same brand of oil was always used; since each gas station in those days only carried their own brand of oil.

    If you changed oil brands at that last oil change, I believe this was the cause of the increased oil consumption you now experience. There are things you can do to undo some of the chemical consequences that brought about your oil consumption. But there are so many doubters and know it alls on this site who prefer myths and slick marketing hype over my direct experience (and that of successful tuners and racers); and they will probably try to convince you that I don't know as much as they do, so I won't waste my or your time by saying anything more about this unless you ask me to. Please refer to my response to your other post on the value of switching to synthetic oil.

  • MrShift@Edmunds 05/07/10 7:40 pm PST

    Just switch back to synthetic next oil change and change it every 5000-7500, and live happily ever after. :)

  • Stever@Edmunds 05/07/10 7:51 pm PST

    The first tech wasn't wrong, but he wasn't right either. You have, like most of us, a regular car. There's no reason not to use a regular oil.

    Your owner's manual simply says to use an oil that displays the "Starburst" certification symbol (they also want you to pay more for the Honda brand - ha!).

    The second tech was completely wrong (he probably didn't have any synthetic around or wasn't told you've been running synthetic, so dumped whatever was handy in and then made up a story for you).

    The owner's manual says you may use a synthetic motor oil if it meets the same requirements listed under the "What type of oil should I use?" section. That is, same weight oil and same Starburst symbol.

    The owner's manual doesn't say not to switch types of oil so I wouldn't worry about using synthetic one time and regular the next. I wouldn't spend extra for synthetic myself.

    The owner's manual also says "There is absolutely no benefit in changing your oil more frequently than recommended in your owner's manual." Just let the Maintenance Minder tell you when to get it changed.

    How To Find Your Car Owner's Manual Online


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5. texases 245
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