What weight Oil does a given manufacturer make and why

Silvic · Nov 24, 2015

I have been using regular old diesel rated oil in my diesels since forever. I am an the edge of switching to synthetic in a couple of them.

The thing I have run up against is this:
manufacturer A only makes 10w-30
manufacturer B only makes 5w-40
and so on.
For gas engines and diesel as well for the non synthetics there is a large choice of weights for any given brand but it seems you are very limited in the synthetics to one or maybe two brands/manufacturers if you go that route. It seems that 15w-40 synthetic is not really available but 5w-40 is the standard. My manual while allowing 5w-40 restricts it to a range that is not really compatible with my operation. I would like to use one brand but that just seems not to be possible.

Anyone know the background on why synthetics are so limited in the weights that any brand has. Basically each brand has one and only one weight synthetic (diesel rated oil)

RalphVa · Nov 24, 2015

Mobil 1 has a whole slew of different weights, but not very many diesel rated. I currently have a 5 quart container of 5w-40 diesel rated, waiting for the 1st oil change either on the tractor or the diesel generator. This range should cover almost any manufacturer's recommendation. I'd rather have 5w-30, but Mobil 1 only comes in this range with the diesel ESP (exhaust system protection, e.g. ashless). Only can get it online and quite expensive; so, I've settled for the local 5w-40.

Rotella also comes in 5w-40. Not strictly synthetic, hydrotreated. I've used it.

You can buy 5w-30 Castrol for VW TDIs at a VW dealership, and, at least the local one here, they don't rip you off.

I just preferred to buy the Mobil 1 because I'm a retired Exxon employee. Have to use the Castrol or the Mobil ESP for my TDI. I just buy the Castrol for its 10k mile changes.

Ralph

Ralph

bdog · Nov 24, 2015

What application is there where 15w40 would work and 5w40 would not? I can't think of one.

From what I understand they both are basically identical at operating temperatures but the 5w flows better when cold for easier startups.

brown40 · Nov 25, 2015

Where they are actually choosing the hydrocarbon mixture they are working/modifying, the manufacturer has to have the proper set up to work the precursors to the finished product... I'd expect they choose their "demographic" that may actually use the product when setting up their systems. As mentioned, the 5w-40 covers everything between. The second number is the working temperature rating, and the first the cold flow rating. If you can use either, the 5w-40 is a better year round oil. After I get through my stock of dino 15w-40 I'm switching to 5w-40 synthetic--tired of molasses in January and punishing start-ups when the block heaters haven't had been running. Supposedly for heavy loading the dino 15w-40 is a "tougher" product and won't shear as much when stressed... don't know if synthetic mixtures work the same or not, but improved stability is one of their selling points.

Copperhead · Nov 25, 2015

A lot of the 15w40 synthetics that are available are synthetic blends and not full synthetics. Full synthetics, by their very nature, have winter flow rates that qualify as 5w40 oil. Doesn't really matter. Both are 40w oils, just with different cold flow rates. Amsoil is the only one I know of that offers a full blown synthetic in a 15w40 variety. All the other synthetic 15w40's from others are blends.

Choices are only limited based on where you are looking. Mobil offers 5w30, 10w30, 5w40, and 15w40 synthetic and blends in HDEO. Same for Rotella, Same for Delo, same for Schaeffer (my choice), same for Safety Kleen, and the list goes on and on and on. Personally, I have moved every one of my diesels over to a 10w30 and have been very pleased with the results. No evidence of any wear increase, much better starting on cold days, and smoother engine operation year round. From my little 1.8L in my NH compact all the way up to the Detroit 12.7L in my semi truck. Everything gets a 10w30 synthetic blend. Darn good value, excellent results.

I was on the full synthetic motor oil game for quite a while, but have moved back to synthetic blends a couple of years ago. The quality of base oil production has dramatically improved in the last 10 years that the differences between Group II, Group III, and Group IV base oils has shrunk so much that the blends make more sense. Neither of these groups is the perfect solution for the broad spectrum. They all have individual characteristics that are favorable. Therefore, I like using a blend which gives me the best qualities of more than one oil base group. And prices that are very cost effective compared to the higher priced full synthetics.

RalphVa · Nov 25, 2015

0w30 passes for use if a 5w30, 10w30 or even a 30w are recommended in your manual.

0w40 or 5w40 passes for use if a 15w40 or 40 weight are recommended in your manual.

Generally xw30 weight is fine for operating in temperatures up to around mid 80s F. Think the charts often show about 86 F. Above that, if a lot of your work is done above 86 F, a xw40 weight is recommended.

HOWEVER, you can generally use a 0w or 5w40 oil in any engine. The only penalty is fuel usage due to higher pumping friction loss of the oil pump (primarily). It will not harm your engine.

The lower the initial (xx) number in the xxwyy game, the quicker your oil pump will get lubrication to the upper parts (the valve train) of your engine.

So, if you can find it, get 0w30 or 0w40 or even 0w20 (for a gas engine) to have high engine life.

I had a VW cabrio not long ago that had a lot of hydraulic valve hammer unless I put 0w30 oil in it. Valve hammer is due to oil draining out of the hydraulic lifters on shutdown. The 0w30 was light enough at startup to allow the oil pump to refill the hydraulic valves quicker and avoid the hammer.

Ralph

Soundguy · Nov 25, 2015

bdog said:
What application is there where 15w40 would work and 5w40 would not? I can't think of one.

From what I understand they both are basically identical at operating temperatures but the 5w flows better when cold for easier startups.

ditto.. I'm trying to think where 15w40 is ok but 5w40 is not??

Copperhead · Nov 25, 2015

That is all pretty much true. On the viscosity recommendation, it all depends on the model and when it was made. The 30w oils in most all the diesel engines made in the last few years works well above the 90F threshold of the older viscosity charts. The charts for my 2005 NH TC33DA shows 30w applicable well above the 90F mark, as does the Lube chart on the factory remanned, built in 2000 Detroit 12.7L Series 60 in my semi truck. 40w is pretty much only a standard in the minds of folks from habit more than knowledge.

The only issue with the lower cold flow is it takes more viscosity improvers to meet a 0wXX rating than it does a 5wXX rating, even though that is synthetic territory. We all pretty much know that base oil, itself, does not break down, but viscosity improvers can and do shear under pressure and can cause the oil to go out of specs in terms of viscosity. Each engine and application are different, and the resulting stresses on a motor oil are different. That is why, myself, I have not had a motivation to go into 0wXX territory, unless I move back to Alaska. For the vast majority of folks in the U.S., a 5wXX would work quite well across the spectrum and provide a lower risk of viscosity improver break down.

buickanddeere · Nov 25, 2015

There is a lot more to be concerned about than viscosity . Most people here appear unaware of API ratings which are vital. For example the wrong motor oil , a high ash four stroke diesel oil will ruin a two stroke Detroit. Some low ash post 2007 diesel oil will cause extra cam/follower wear.