If your bike manual suggests 10W40 engine oil, would it be safe to use 5W40? Thoughts and opinions please.
Thanks!
Thanks!
|
|
|
Engine Oil Question?
- Thread starter bronsondm
- Start date
It has to be used with the proper combination of products/settings and insurance providers.
For example, if you go down to 5W40, you have to increase the amount of fuel stabilizer over the winter (just not the pink stuff). You should also increase the front tire pressure 2 pounds more than what the manual says, and the rear 3 pounds.
Also, if the manual recommends 87 octane gas, fill it up with up 91, unless you insurance provider is State Farm, then use 89.
Of course, if you're using Royal Purple, none of this is applicable. Just put in whatever viscosity you want and then burn some of the new $50 bills.
I'm kidding. Surely that's evident. Sure it's safe. But why change from what's recommended (probably not simply "suggested") by the manufacturer?
No offense intended, but if you know something the manufacturer didn't, you wouldn't be asking for feedback.
Last edited:
You are absolutely right, the only reason why I ask is because I have a 4L jug of Rotella T6 5W40 sitting in the garage and if its safe to use, why burn more $50 dollar bills?
That makes sense.
I'd never heard of that (oil does not interest me much) so I did some searching. Seems pretty popular.
What bike are you running? I know my 250's service manual indicates varying oil viscocities based on usage temperate. There is a very large sweet spot which covers just about 90% of riding conditions and which recommends 10w40, but it certainly indicates tolerance for other viscosities.
Use whatever. I think Rosey Toes uses 5W40 when I get it changed there, but I throw 10W40 into it if it ever eats oil (GS500Fs are known to eat oil), engine hasn't exploded or made funny noises for 15,000 so who cares lol
EDIT: Just don't use NOS.
EDIT: Just don't use NOS.
Last edited:
1
19891989
Guest
On my previous bike (Ninja 250) and my current bike (Gsxr 600) 10W40 is recommended but I use 5W40 and it works perfectly fine in both.
1
19891989
Guest
That's the same one I use and many others use that as well, so it will be fine. I would never use anything that would hurt my precious little barbie <3
I can understand if it happened once by mistake or you were in a pinch and had to use the 5W.
But why would you use it if the manufacturer recommends the 10W?
Im only asking because I am curious, maybe I'm missing out on something!?
5W40 is potentially less durable than 10W40, all other things being equal, which they aren't. It shouldn't hurt anything, if you change your oil frequently like most people do.
The first number relates to the base viscosity of the oil, and the second number is the max viscosity of the oil when it is at it's peak design temperature. (Go past that and the viscosity starts going down again). The high viscosity is achieved by viscosity modifiers, which are temperature sensitive polymer chains (they are compact when cold and straighten out when hot). These chains are broken down over time by shear forces in the motor - the peak useful viscosity of oil goes down over time. Ideally, the less you have to boost the viscosity of the oil, the better.
I hope that made sense, and I hope I didn't make any of that up.
The first number relates to the base viscosity of the oil, and the second number is the max viscosity of the oil when it is at it's peak design temperature. (Go past that and the viscosity starts going down again). The high viscosity is achieved by viscosity modifiers, which are temperature sensitive polymer chains (they are compact when cold and straighten out when hot). These chains are broken down over time by shear forces in the motor - the peak useful viscosity of oil goes down over time. Ideally, the less you have to boost the viscosity of the oil, the better.
I hope that made sense, and I hope I didn't make any of that up.
In that case, 5W40 it is!
When you're reading the viscosity numbers on the oil - (10W-30, 15W-40, 10W-60, etc.) - - the first number relates to the viscosity of the oil at 0 degrees C and the second number is the viscosity at 100 degrees C. (what is reasonably assumed to be "operating temperature"). A 10W-40 will flow like a 10 weight oil at 0 degrees and flow like a 40 weight when hot. When they're cold, a 10W-30 and a 10W-40 will both have the same viscosity - or very close, but the 10W-30 will be thinner at operating temp. So, your 5W-40 is a bit less viscous, on start-up (a good thing) than a 10W-40, but at operating temp., they are the same (more or less). On start-up, you want the least viscous oil you can get - pumps and flows more easily, and is less likely to activate the by-pass valve in your oil filter.
TwistedKestrel has it exactly right - I would only add that, the VII's (viscosity index improvers) he's referring to, are not generally added to a quality synthetic oil, as they are not needed - one of the properties of synthetic oil,is that it is inherently viscosity stable, through a wide range of temperatures.
As far as your Rotella 5W-40 - myself and thousands of others have been using it in our bikes, with excellent results. For the money, there's not much out there that can touch it.
TwistedKestrel has it exactly right - I would only add that, the VII's (viscosity index improvers) he's referring to, are not generally added to a quality synthetic oil, as they are not needed - one of the properties of synthetic oil,is that it is inherently viscosity stable, through a wide range of temperatures.
As far as your Rotella 5W-40 - myself and thousands of others have been using it in our bikes, with excellent results. For the money, there's not much out there that can touch it.
Wouldnt some of the clearances be bigger in a cold engine than a warm engine? Cant understand why they would recommend 10W when 5 W is better?
ifiddles
Well-known member
WOW...what an awesome answer...thanks, now I understand what the numbers mean...
Yes - all the clearances are wider in a colder engine, than a hot one - but a more viscous oil is still not going to flow into these "clearances" as readily or as quickly as a less viscous oil.
To the best of my knowledge, there is no regular oil (non synthetic) that is a 5W-40. That would require so much VII added to it, that it would diminish its function as a lubricant - The long-chain polymers referred to in TwistedKestral's post, have zero lubricating ability. This is one of the reasons that you won't find a regular (dino) oil for diesel applications, lighter than 15W. Mack, Cummins, Detroit, etc. haven't been able to get an oil built, in 10W-40, that can stand up to the loads their diesels put on the oil - best they can do, is a 15W. Synthetic, on the other hand - because it requires no VII's, you can get a 5W, or even a 0W for HDEO applications.
I suspect that the reason that 10W-40 shows up as a recommendation in the owner’s manual, is that, if they said you should use a 5W, or a 0W - they are basically saying you should be using synthetic oil and not "regular" oil. Porsche, BMW, etc. can get away with that - I don't see it being a popular "recommendation" for somebody buying a Chev or a Honda. In addition - the "engineers" don't write the owner’s manual - I'm sure their input is taken under advisement, but I'm just as sure that "marketing" has the final say.
Just for the record - the less viscous your lubricant is on start-up, the better. If you can find a 0W-whatever, whose operating temp. viscosity is in the correct range for your bike/car/truck and you're willing to part with the extra coin to buy it, then do it.
Further to the above (excellent) post ... the manufacturer has established that 10w40 is cheaper and "good enough", even though 5w40 synthetic (without an excessive amount of VI improvers) might be "better".
I have a European car that calls for 5w40, and there are typically only a few viable choices (generally, Rotella T6 or Mobil 1 Turbo Diesel Truck, or specialty brands only seen at European-car specialist shops) and they are all synthetic. I don't have a problem with it, because I "get" that paying 3 times as much for oil that I only have to change 1/3 as often is the same money in the long run and less aggravation (because I only have to crawl underneath one-third as often) but it doesn't work for the general public who only want the cheapest oil change possible and don't pay attention to anything else.
|
|
|
|
|