What Viscosity Oil

[Lakeman1]

I made a mistake, disregard everything I didn't say here.

[DriVer]

Originally Posted by Pete & Linda

I made a mistake, disregard everything I didn't say here.

OK Pete! No problem!

[Lakeman1]

Mike I was watching TV and looking at the Workhorse manual and it said to use 15 W 40 oil and I knew that didn't sound right. I have been using 10 W 30 Mobil 1. So I posted a tread about it and hit summit about the time I realized I was looking at the DIESEL specs!! Oh well?

[DriVer]

Originally Posted by Pete & Linda

Mike I was watching TV and looking at the Workhorse manual and it said to use 15 W 40 oil and I knew that didn't sound right. I have been using 10 W 30 Mobil 1.

That's the oil viscosity that I would recommend that we use use in South Carolina.

[Lakeman1]

Yes, hope ya'll are doing well.

[JohnRR]

I was in Syracuse NY a couple of months ago when I needed an oil change, not knowing any one to trust I looked up some tow companies from another tow site for a place to get it done. The only oil they carried was Rottella 15W40 and being how I've used that in all my other gas trucks for years that's what we put in the 8.1 and honestly so far I can't tell the difference.

Now when I change it again here at home I'm thinking of going to the factory recommended 5W30 but using synthetic oil along with a 2 qt filter.

edit; I have to admit at the moment I can't really recall whether the book showed 5W30 or 10W30.

[DriVer]

Originally Posted by JohnRR

edit; I have to admit at the moment I can't really recall whether the book showed 5W30 or 10W30.

JohnRR, The book actually shows "both". If you don't use your motorhome in cold startup temperatures of 0°F and below you can use 10W-30.

There will be more written about 15W-40 however my position is that the oil is too viscous and will negatively impact MPGs. A 15W-40 oil installed in a new engine may also introduce complications if there is a warranty claim on the new engine.

[JohnRR]

Not having a tremendous amount of experience checking the MPG with this 8.1 being new (to me) I don't see much difference with it. I used the 15W40 because that's what they said they had and at the time I was more interested in using someone I knew (like using a parts supplier from this site) than an unknown oil change source on the road.

In the past using the 15W40 with all the tow trucks over thirty years one of the very last things on the consideration list was MPG. I did Ryder truck rentals for over 20 years and they used 15W40 in both their diesel & gas units which is what got me started with doing it since it was good enough for them and I had a 275 gallon tank of it in the shop.

Next change I'm sure will be synthetic to try something "new" and maybe perk up the MPG a bit. I'm also putting a drain valve in place of the drain plug so I can drain the engine oil when it becomes due into a plastic container without messing up the drain site, the drain valve will have a drain hose on it.

[Topflite51]

Most charts that I have seen have shown 15W40 as being tested down to -13F or -15F, so unless you operate below that you did not hurt anything. If you consistantly operate at temps above 80 and do a lot of stress driving, like in the mountains, 15W40 is probably a good thing.

There are an awful lot of people that do use 15W40 or even 15W50 with no ill effects on their motor.

You could however experience a drop in fuel mileage, just how much who knows.

If you were under a manufacturers warranty and a problem occurred, well there are 2 sides on that argument. If you are on an aftermarket policy, I wouldn't use anything that was not specified in the manual. I'd probably ask them what brand of wax and how often they wanted me to polish the rig.

[al koffman]

Here is a blurb about oil viscosity. I still use dino oil and on summer trips I use a straight 30 weight Castrol.

What is Viscosity?

"Viscosity is the measure of how thick an oil is. This is the most important property for an engine. An oil with too low a viscosity can shear and loose film strength at high temperatures. An oil with too high a viscosity may not pump to the proper parts at low temperatures and the film may tear at high rpm.
The weights given on oils are arbitrary numbers assigned by the S.A.E. (Society of Automotive Engineers). These numbers correspond to "real" viscosity, as measured by several accepted techniques. These measurements are taken at specific temperatures. Oils that fall into a certain range are designated 5, 10, 20, 30, 40, 50 by the S.A.E. The W means the oil meets specifications for viscosity at 0 F and is therefore suitable for Winter use...
...Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.
Multi viscosity oils are one of the great improvements in oils, but they should be chosen wisely. Always use a multi grade with the narrowest span of viscosity that is appropriate for the temperatures you are going to encounter. In the winter base your decision on the lowest temperature you will encounter, in the summer, the highest temperature you expect. The polymers can shear and burn forming deposits that can cause ring sticking and other problems. 10W-40 and 5W-30 require a lot of polymers (synthetics excluded) to achieve that range. This has caused problems in diesel engines, but fewer polymers are better for all engines. The wide viscosity range oils, in general, are more prone to viscosity and thermal breakdown due to the high polymer content. It is the oil that lubricates, not the additives. Oils that can do their job with the fewest additives are the best. "

[DriVer]

Originally Posted by al koffman

Here is a blurb about oil viscosity. I still use dino oil and on summer trips I use a straight 30 weight Castrol.

Not totally a bad choice at all.

Multi viscosity oils are one of the great improvements in oils, but they should be chosen wisely. Always use a multi grade with the narrowest span of viscosity that is appropriate for the temperatures you are going to encounter.

I have written many posts about this and is yet another reason why I like to use 10W30 rather than 5W30.

VISCOSITY

Engine oil viscosity (thickness) has an effect on fuel economy. Lower viscosity oils can provide better economy; however higher temperature weather conditions require higher viscosity engine oils for satisfactory lubrication. Using any oil viscosity other than those recommended could cause engine damage.

Gasoline Engines

– For all temperature ranges the preferred oil for your engine is SAE 5W-30. However, you can use SAE 10W-30 if temperatures stay above 0 degrees F (18 degrees C). For heavy-duty driving in summer temperatures, above 40 degrees F (4 Degrees C), there can be an advantage to a single-viscosity straight SAE 30. Refer to adjacent chart.

Note:
SAE 10W-40 has been removed from all Workhorse recommendations. Research Laboratories
have found generally a 1.2% fuel economy penalty compared to 10W-30. Of the oils surveyed some contained inadequate additives and some did not meet the 10W-40 viscosity requirements. Testing showed 10W-40 oils tended to be more prone to high mileage ring sticking. These problems appeared more frequently in 10W-40 oils. Workhorse also does not recommend SAE 20W-50 viscosity oils.

[JohnRR]

temperatures stay above 0 degrees F (18 degrees C)

That sounds like my temperature target range, well actually more like above 35 degrees.

[Midniteoyl]

Actually... I use 15W-50 Mobil in my Audi during the Summer and 0W-40 in winter... I get better mileage and less valve train noise on the 50...

[max49]

I think everybody has an opinion on oil and every one says,"they never had a problem"
Other than running with no oil, I don't remember any failures because the oil was'nt not doing it's job.
It still makes sense to me that thicker oil will lubricate better and stay on longer but I've got 10W30 in all my vehicles now.
For what ever reason, (emissions and fuel economy IMO) the trend is toward lighter weight oil. Maybe soon we will be using WD40 in our engines.