The myths of synthetic oil, or are they?

I've done a bunch of Google searches and can't find anything specific to motorcycles (maybe I'm using the wrong key words) and Ive also tried searching this forum but want to get a final answer on this seemingly controversial topic.

When is it too late to switch to synthetic oil? Or will it ever be too late? Everyone seems to say something different and I don't know who the heck to believe :/

My Ninja 250 I've been using Shell Rotella T6 for most of the time I've owned it but the FZ6 I just bought has a lot more mileage than my Ninja did (It has 27k on it). The last owner when I emailed to ask him if he was using synthetic oil just basically told me that it was a myth and one could switch back and forth and that he used Castrol oil. I'm assuming he meant non synthetic but he didnt specify and I don't want to harass the guy so I just want to know if its OK to use the Shell Rotella T6 when I change the oil this week.

I want to take good care of my new baby so if there's a chance its not a myth then maybe I should just stick to the dino stuff. The possibly a myth seems to state two reasons why it may be bad to switch to synthetic late in the game , one being if a bike has any oil leaks (I've only owned the bike for 2 days now and it seems as if it doesn't so far) as synthetic is thinner and can make it leak more and the other reason is related to gunk somehow getting in the engine because of the now more efficient oil (or something like that).

Sorry to bother everyone with this question which I'm sure has been asked in one form or another 1.5 million times.

I've switched back and forth for my cage over the years. for my most recent car I paid a shop to do standard changes with regular oil during the warranty period then started doing synthetic changes when the car was 4 years old. For a period there I was also using a synthetic blend oil. The car doesn't care what oil was used. it was just important to change it at recommended intervals.

For the bike I use only synthetic oil. I have no idea what the first owner used for the first 2900 miles. I don't think it will matter at all if you switch back and forth from regular to synthetic. The only theory I subscribe to is you probably don't want to use synthetic oil in a motor with 0 miles on it since the stuff is so slippery and you don't want to hinder normal break in.

You are going to get a smattering of different opinions here.

I've asked this question to 3 different mechanics, two of which are motorcycle mechanics and former mechanics for racing teams. The verdict is that is doesn't matter if you switch between synthetics and conventional. It's not going to ruin the engine. Just follow the recommended weights and changing intervals that the manufacturer specifies and you'll be fine.

My Triumph has had synthetic in it since I drove it off the show room, and is recommended to be changed every 6000 miles by Triumph. I've seen special "break-in" oils out there but have no idea if these are advantageous.

I will say that in my 2002 VW Golf, which tends to consume oil more than other cars I've owned: it consumes synthetic oil slower than conventional oil. Something about the synthetic 5W-30 tends to holds up better.

My 2¢ for what it's worth

I'm not sure about the correctness of this information or the reliability of the source, but it does discuss a time when the author is pretty emphatic about NOT using synthetic oil for break-in, specifically in regard to the compression ring and cylinder surfaces. I've heard differing opinions regarding cam shaft love break-in. Not sure about that.

http://www.ntnoa.org/enginebreakin.htm

mikw73 said:

I'm not sure about the correctness of this information or the reliability of the source, but it does discuss a time when the author is pretty emphatic about NOT using synthetic oil for break-in, specifically in regard to the compression ring and cylinder surfaces. I've heard differing opinions regarding cam shaft love break-in. Not sure about that.

New Engine Break-in Procedure

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Not using it during break in seems to be a pretty common opinion (or fact?). Its if switching back and forth or starting it too late is okay that carries the till death argument around it.

Take it from an Auto Tech that has more than 20 years experience and owns a Napa Auto Care Center. It's fine to switch between synthetic and dino oil, won't cause leaks. Did you know that some cheaper synthetics will not perform as well as good quality conventional oils.

The only time you don't want to use a synthetic is during the break in period as stated above.

Goop said:

My Triumph has had synthetic in it since I drove it off the show room

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This got me thinking...so I asked the dealer (who's actually open on Sundays), and:

I stand corrected, the guy at the service counter who told me the above was wrong. The first fill up of oil they did was conventional, then at 600 miles they went to Castrol full syn.

Gotta keep on top of these guys.

Ruggybuggy said:

Take it from an Auto Tech that has more than 20 years experience and owns a Napa Auto Care Center. It's fine to switch between synthetic and dino oil, won't cause leaks. Did you know that some cheaper synthetics will not perform as well as good quality conventional oils.

The oil time you don't want to use a synthetic is during the break in period as stated above.

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You're avatar is going to give me nightmares

happyker said:

Not using it during break in seems to be a pretty common opinion (or fact?). Its if switching back and forth or starting it too late is okay that carries the till death argument around it.

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Correct. I forgot the original question. :BLAA:

I don't think switching back and forth matters.

Higher mileage motors are supposed to benefit from heavier weight oil, and synthetics and the likelihood that a better viscosity index improver (VII) package is in them make more sense to me. Also, the Rotella T6 is the only 5w40 oil I know, so that way the motor gets the low temp thinness Yamaha specs for it and a higher warm weight. VIIs do break down though, so the 5w40 may not last as long as a comparable 15w40 synthetic.

Goop said:

You're avatar is going to give me nightmares

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You should try coming home to them.

Synthetic is not any slicker, thinner etc. than dino oil, switching back and forth wont cause problems. The main advantage to synth. is that the additives and viscosity packages wont break down as fast over time. You can switch back and forth as much as you want just be sure to use high quality oil as opposed to the el cheapo and there should be no problem. VWs do require synthetic (at least the turbo cars) because of heat issues causing the oil to sludge, but unless you do a low oil capacity turbo motor like they did you shouldn't see any problems