[TomJohnston]

I hate to bring up an oil question but......I have a 2014 C5. As you know, the books insist using a 20/50 or 15/50 Semi-synthetic. I'm aware the engine and transmission are lubed by the same oil. I know what you all will say so I'm only asking an OPINION.
Since my riding is for relatively short distances and becoming tame (I'm 70), how bad would it be to use a 15/40 full synthetic oil. I'm know you all will say NO, and vote down my reason why I want to.
I have been on the road for 54 years. New York to Japan...Pennsylvania to Key West. Thousands and thousands of miles. I've tried all the witches brews and snake oils over the years and, of course, no miracles. However, I recently used a highly touted , big name oil in my 33 year old BMW. I was amazed at the differences. Throttle response was much better, accompanied by cleaner shifts, smoother running and better everything.
I want to use it in the RE and wonder what you guys feel about one grade drop in viscosity. I'm reluctant to name the oil for obvious reasons but it is a common brand and has a good reputation. ....answers???

[Ducati Scotty]

Don't use any 'energy conserving' oils, they can cause a wet clutch to slip.  If you won't be riding much in warm/hot weather (over 80F) I'd say you'd probably be fine.

FWIW, my 2014 Mazda specs 0w20 in the US and 5W30 everywhere else in the world.  The thinner oil provides plenty of protection but with less resistance, you get higher mileage.  Don't know if there's anything different about the US engine, but I seriously doubt it

Scott

[Craig McClure]

I hate to bring up an oil question but......I have a 2014 C5. As you know, the books insist using a 20/50 or 15/50 Semi-synthetic. I'm aware the engine and transmission are lubed by the same oil. I know what you all will say so I'm only asking an OPINION.
Since my riding is for relatively short distances and becoming tame (I'm 70), how bad would it be to use a 15/40 full synthetic oil. I'm know you all will say NO, and vote down my reason why I want to.
I have been on the road for 54 years. New York to Japan...Pennsylvania to Key West. Thousands and thousands of miles. I've tried all the witches brews and snake oils over the years and, of course, no miracles. However, I recently used a highly touted , big name oil in my 33 year old BMW. I was amazed at the differences. Throttle response was much better, accompanied by cleaner shifts, smoother running and better everything.
I want to use it in the RE and wonder what you guys feel about one grade drop in viscosity. I'm reluctant to name the oil for obvious reasons but it is a common brand and has a good reputation. ....answers???

I've been using 15/50 Mobil 1 in my 2010 G5 with no problems, & it runs great.

[Arizoni]

Tom:
Like Ducati Scotty says, if your riding easy and in cool temperatures (below 80*F) the 15w40 weight oil should work all right provided it meets JASO MA, MA1 or MA2 requirements.
Those are the requirements to make sure the wet clutch won't slip under load.

If you are going to do any fast, spirited riding the low amount of ZDDP (Zinc dialkylDithioPhosphates) in automotive oils may cause some extra wear on the transmission gear teeth, piston rings and cylinder wall. (Anyplace where there is shearing action).
Also, if your going to be riding in temperatures in the 90's or higher the extra thickness of the 50 weight oil will help to keep the oil film where it's needed.

[suitcasejefferson]

I'm in AZ, where it has been known to drop below 80F in the winter once in a while. But I wouldn't even consider using anything thinner than a 15w50 or 20w50 in a motorcycle, especially an air cooled single or single crankpin v-twin. These engines put a heavy load on the con rod and crank bearings, and you need an oil with all the load bearing ability you can get. I have owned singles, parallel twins, v-twins, triples, inline and horizontally opposed fours, and a horizontally opposed six (Goldwing) I've never use anything but 20w50 in any of them, and never had an engine failure. Harley recommends only 20w50 in their engines.

I don't see any problem with any type of oil, conventional, semi synthetic, full synthetic, car, or motorcycle specific, as long as that last number is a 50. I'm using a very expensive full synthetic motorcycle specific oil in the RE, but I intend to follow the oil change intervals in the manual. I have a couple of other bikes I use cheap conventional 20w50 oil in, but change it every 1000 miles.

10w40 or 15w40 might work ok in a four or six cylinder engine, they do not have anywhere near the stress on the bearings as a single, especially a long stroke single like the RE.

[TomJohnston]

Message received and understood. Just for reference.....the oil was Royal Purple. The BMW loves it but I will pass for a 15/50.........Thanks!

[barenekd]

Don't use any 'energy conserving' oils, they can cause a wet clutch to slip.

Hey can do a lot more damage that that in a motorcycle. The gears can get torn up from the lack of cushion,and bearings that are not designed for that stuff can go away. The car dealers are trying everything they can to get better mileage. They're designing engines to run on that 20 wt oil. Motorcycles aren't there yet (cars don't turn 15,000 RPM). Stick to motorcycle specific oil. If your justputteringaround the40wt would probably be OK. Enfields aren't noted for running hot. Some of us 70+ers still flog the hell outta the bikes though! Even though it is true that the older I get the faster I was!!
Bare
Bare

[Ducati Scotty]

Are the cars being designed for 20 weight oil or are they just putting it in the same old engine?  Like I said, the US Mazda gets 0w20 and the rest of the world gets 5w30.  Is there really a difference or is it just running lighter oil in the US engines to get that tiny bit more MPG?

Scott

[suitcasejefferson]

I recently retired from a 32 year job as a fleet service technician for the City of Chandler. We used only American brand vehicles, because city policy required it. They were all supposed to use 5w30 oil. But my supervisor was an old school mechanic like me, and we put Rotella 15w40 into every vehicle we had. We bought several 55 gallon barrels of it at the time. We never had a single oil related engine issue. The 5w30 recommendation goes back nearly 30 years. It id NOT what is best for the engine, it's what's best for the EPA. I use 15w40 in my '01 Chevy (I used to get free oil) and will be buying a new car in less than a year. I will also use 15w40 in that as well.

[TomJohnston]

Regarding the mention of Rotella oil.....I have heard great things about it. I understand it's a Shell Oil product. But when I look for it, I only find 15/50 Synthetic Rotella with a note on the bottle "for Diesel engines". Is that okay and just saying it's ALSO good for diesels or is that just for diesel use

[ROVERMAN]

As to the question of manufacturers lightening oil. My wife's 08' Honda used 5/w/20, her 12 model with the same engine specifies 0/w/20. I asked Honda, no internal changes were made, purely for less friction/better mileage. As soon as it was broken in i started using 5/w/20 Castrol Edge.
Roverman.

[gashousegorilla]

 More Car specific, but a good read on oil....

http://www.bobistheoilguy.com/motor-oil-101/

[suitcasejefferson]

More Car specific, but a good read on oil....

http://www.bobistheoilguy.com/motor-oil-101/

I have read that before, and other similar information in trade magazines. I grew up with the old way, and will stick with it. Notice RE recommends 15w50 oil, Harley-Davidson recommends 20w50 oil. They do not recommend 0w10. My Vulcan 750, which is liquid cooled, says 10w40 right on the oil filler cap, but the manual also recommends up to 20w50 (which is what I use) for higher ambient temperatures. And as far a liquid cooled engines, ambient temperature is still very important when choosing an oil. A liquid cooled engine does NOT run at a constant temperature regardless of ambient temperature. Every liquid cooled bike I've ever had always ran much hotter in the summer than in the winter. In the winter, my VN750 runs in the low to normal range on the gauge, in the summer it runs way over toward the hot side. A "liquid cooled" engine is still air cooled, it just has an extra step. Most liquid cooling systems on bikes are marginal, especially in a place like Phoenix, AZ.

The numbers DO matter. A 20w50 oil is measurably thicker than a 10w40 oil at any given temperature. I use straight 60w oil in my drag race car. The engine was built for that oil, with the proper bearing clearances. In an engine, heavier oil does have more fluid friction, but it is a worthwhile trade off, because it protects your bearings.

This thing about wear at start up is largely a myth under most circumstances. If you ride the bike often, all the internal parts of the engine stay coated with oil, and the thicker then oil, the longer they will stay coated. Thick oil sticks to metal, while thin oil will run off faster. I have taken apart engines that sat for over a year, and found everything was still coated in oil. Thicker oil also provides better ring seal. In an older engine that is burning oil, switching to a thicker oil will lower oil consumption, and also provide more cushion for worn bearing clearances, making the engine last longer.

As for diesel oil, you can use it in any engine. It used to be much better than regular oil, because it had a much higher content of zinc and phosphorus, which are good for engines. This was also the case with motorcycle specific oil. But more recently, and again because of the EPA, these beneficial elements are being removed from all oils.

[Kevin Mahoney]

I can say with 100% certainty that 15w40 full synthetic is fine. No worries at all and was tested for the bike. It was (and might still be) the recommended oil.  It is hard to find in some markets which led to the change.
Truth is dino oil is OK but they won't say it publically and I don't recommend it while under warranty. Let the fighting begin

[Arizoni]

Regarding the mention of Rotella oil.....I have heard great things about it. I understand it's a Shell Oil product. But when I look for it, I only find 15/50 Synthetic Rotella with a note on the bottle "for Diesel engines". Is that okay and just saying it's ALSO good for diesels or is that just for diesel use

Rotella is made for diesel engines and it does contain quite a bit of the zinc phosphate (ZDDP) that's good for motorcycles and their transmissions.
Other additives that are in it are equal to or better than the oils made for common automobiles.

The reason the label stresses the diesel use is because the EPA thinks ZDDP can damage catalytic converters and as they have mandated that all automobiles have these converters they don't want Rotella being used in them.  Rotella isn't the only oil made for diesel engines but it is one of the more easily found brands.