a new oil question??

[Guest]

Last two summers I went to 20w50. This year I am not going to do that. I only have 600 miles on the 10w 40 that is in there and that is just wasteful. Here is my non dilemma ... I am using Lucas Full synthetic 10w40 for wet clutch bikes.

I will probably not have to do an oil change proper until august. While my bike doesnt seem to burn oil I never get all the leaky spots and now and again have to top up the oil.

It is a breeze to find the same lucas oil but .. in 20w50. Can I just use that to top up even though I have 10w40 in there now. I estimate on past experience needing about < 1/2 qt throughout the summer.

For whatever reason its tough finding a single qt of the 10w40

[Rich82GS750TZ]

Wow. My local Walmart has plenary of 10W40 all the time in single quarts or 5 quart jugs. I use Dino though, not synth.

[Boriqua]

Wow. My local Walmart has plenary of 10W40 all the time in single quarts or 5 quart jugs. I use Dino though, not synth.

Of Lucas full synthetic 10w40 motorcycle oil!? They hardly have it at the car places here.

I dont want to mix brands or type .. I just want to top up my 10w 40 with 20w 50 when need be until my next oil change.

[Nessism]

Mix away. You can even mix brands without issue.

[Rob S.]

...I use Dino though, not synth.

Me too. On the '82, that is. In the first place, she seeps a little. Not enough to be of concern on a garage floor, but I have newspapers on the living room carpet where she resides. I guess I bought into the notion that synth, being thinner, will seek out leaks.

I also believe in going by the book. The '82 book says Dino, 10-40. I know synth wasn't available back then, so she was raised on Dino, and she's no spring chicken.

In my 2016 Sporty, though, she came new with synth, that's what the book recommends, and that's what she gets. Of course the 'book' says HD brand. Yeah, I'm a sucker.

[Steve]

... It is a breeze to find the same lucas oil but .. in 20w50. Can I just use that to top up even though I have 10w40 in there now.

No problem, mix away. As Nessism suggests, don't hesitate to mix brands, if necessary, but I would add my preference to that. If you mix brands all the time, some of the additive packages might not play well with each other. For a one-time occurrence, or topping off while on a trip, use whatever you can find, as long as it is proper for the bike.

I guess I bought into the notion that synth, being thinner, will seek out leaks.

Not sure if it's just a notion or an outright myth, but synthetic oil is not "thinner". 10w-40 is 10w-40, regardless of origin.

In my opinion, what has perpetuated that myth of "synthetic oil causes leaks" is that many (most?) synthetic oils have additional detergent packages in them. Those detergents clean the inside of the engine rather well, even cleaning off the back side of crusty deposits that have formed at a gasket leak. "Dino" oil will just flow by, or even add to, the deposits, but synthetic will clean them off. Eventually, it will clean it off right down to the original leak that had been plugged with Dino oil.

Synthetic oil does not cause leaks, it just finds the ones that were already there.

.

[Skinner]

Synthetic oil does not cause leaks, it just finds the ones that were already there..

When I bought my Katana there were no visible oil leaks anywhere. I checked it over thoroughly, even looking for signs on the PO's garage floor, which was spotless. I asked the PO what he was using for oil and he said Castrol 10W40 conventional motorcycle oil. I brought it home, drove it a bit then put it away for a winter of restoration and repairs. No leaks. In the spring I filled it up with Rotella 5W-40 full synthetic and all was well, for about 2 weeks. Then the leaks started. Mostly just small, seepy leaks around the head, etc., in places that I didn't touch. But the main one was from the starter motor o-ring. To make a long story short, when I pulled the starter motor the o-ring was flattened and hard. It actually broke when I removed it. The only thing that could have been preventing a leak at this point all along, IMHO, was a buildup of crud over the years. The synthetic oil took care of the crud and provided me with a nice, messy leak to fix.

Cheers!
K

[Boriqua]

I have been using the synthetic since I bought the bike. Hasn't caused any leaks. I recently was getting a leak from the cam chain tensioner that I didn't spot but I snugged up the mounting screws and it's gone. The leaks I do get are only of my own doing. I checked the valves as part of the reawakening of the bike and bought a new gasket but with some 20 screws and no torque wrench that will go down low enough I put the screws on a bit past finger tight. A thousand years ago, or in the early 80's I broke one of those screws on a gs and now they terrify me. So.... I can go a bit no leaks then I see some grunge and snug a screw and it goes away for a bit only to pop up somewhere else at the valve cover weeks later. The guy before me had used goop but I went to a traditional gasket. The rest of the engine holds oil without issue after about 4500 miles of synthetic. The lucas oil has a ton of detergents and I ride in 110f at times so if it were gonna leak it would have

[Rust_to_Redemption]

I have been using the synthetic since I bought the bike. Hasn't caused any leaks. I recently was getting a leak from the cam chain tensioner that I didn't spot but I snugged up the mounting screws and it's gone. The leaks I do get are only of my own doing. I checked the valves as part of the reawakening of the bike and bought a new gasket but with some 20 screws and no torque wrench that will go down low enough I put the screws on a bit past finger tight. A thousand years ago, or in the early 80's I broke one of those screws on a gs and now they terrify me. So.... I can go a bit no leaks then I see some grunge and snug a screw and it goes away for a bit only to pop up somewhere else at the valve cover weeks later. The guy before me had used goop but I went to a traditional gasket. The rest of the engine holds oil without issue after about 4500 miles of synthetic. The lucas oil has a ton of detergents and I ride in 110f at times so if it were gonna leak it would have

A 1/4 drive torque wrench is great in this situation. You can get one off Amazon that will go down to 1 nm for like 40 bucks. Might not be super accurate (think its +/- 4%), but its more accurate than my interpretation of what 10nm should be. Never had an issue with bolts loosening or valve cover gasket leaks since I started actually torqueing to spec, did have sporadic leaks before that.

[Boriqua]

A 1/4 drive torque wrench is great in this situation. You can get one off Amazon that will go down to 1 nm for like 40 bucks. Might not be super accurate (think its +/- 4%), but its more accurate than my interpretation of what 10nm should be. Never had an issue with bolts loosening or valve cover gasket leaks since I started actually torqueing to spec, did have sporadic leaks before that.

Going to have to add that to my next Amazon order!!!

[wymple]

No problem, mix away. As Nessism suggests, don't hesitate to mix brands, if necessary, but I would add my preference to that. If you mix brands all the time, some of the additive packages might not play well with each other. For a one-time occurrence, or topping off while on a trip, use whatever you can find, as long as it is proper for the bike.



Not sure if it's just a notion or an outright myth, but synthetic oil is not "thinner". 10w-40 is 10w-40, regardless of origin.

In my opinion, what has perpetuated that myth of "synthetic oil causes leaks" is that many (most?) synthetic oils have additional detergent packages in them. Those detergents clean the inside of the engine rather well, even cleaning off the back side of crusty deposits that have formed at a gasket leak. "Dino" oil will just flow by, or even add to, the deposits, but synthetic will clean them off. Eventually, it will clean it off right down to the original leak that had been plugged with Dino oil.

Synthetic oil does not cause leaks, it just finds the ones that were already there.

.

IMO, you are right that it is not "thinner". I really am unaware of the science of it. But anyone who's ever poured cold oil knows it flows much more easily, which may be the same to most folks, and myself, as being thinner.

[Rob S.]

IMO, you are right that it is not "thinner". I really am unaware of the science of it. But anyone who's ever poured cold oil knows it flows much more easily, which may be the same to most folks, and myself, as being thinner.

Ah, the plot thickens! (Thins?)