Convetional 15w40 vs Synthetic?

Right on! I have oft wondered why folks feel they need to add something to their oil. On one hand, they have almost a religious loyalty to a particular brand of oil, then they seem to think it isn't good enough that they need to add Lucas Ostrich Snot to it.

 

Still trying to find the additive package of LOS. From everything I have seen from what others have sent it to the labs, LOS is nothing more than a 150w base oil... no additives of any kind.

Either way, here is a group of 4 samples from my factory remanned S60 with over 500,000 miles on it. The first two (most recent) are from using a 10w30 syn blend and the second two from 15w40 syn blend. The 10w30 is working quite nicely. The latest sample shows the lowest wear numbers. The 10w30 is holding viscosity and TBN much better than the 15w40. Just the oil, no goofy stuff added.

 

What's your feeling about using 10w30 in summer ambient temps <75ish...?

That's when Cat backpedals to heavier grades.

 

I remember testing it out a before my inframe a few years ago in the fall. Oil PSI dropped about 5 lbs. I didn't like it so I switched back to 15W40 but the oil PSI never did recover. I wasted money on a bearing roll in about a year after that and the PSI popped back up 5 more psi.

 

Well, the OEM lube manual for mine shows using 10w30 approved for the same range as the 40w oils. And I am not really sure what the ambient temp has to do with anything when engine is at operating temp in a water cooled system. 1000F at the turbo is still 1000F irregardless of winter or summer. And engine oil is cooled by the cooling system and never gets above engine coolant operating temperature. I suppose if we were talking about air cooled motors, it might be something to consider. Now does Cat backpedal or just some tech in a shop?

Well, you did say that you had to do bearings a year after trying 10w30, so I find it pretty doubtful that the 10w30 caused the problem without some serious evidence of such. Like oil samples from before and after using 10w30 showing that wear metals from bearing escalating. Oil pressure does not totally correlate to proper lubrication. Heck when my engine is cold, I get 62 PSI on my S60 at startup, but no one would suggest it is getting the best oil protection at a cold startup as opposed to when it is warmed up. And oil pressure is a measure of resistance thru the motor, oil filter, etc. A few PSI lower pressure from a 10w30 as opposed to a 15w40 could be primarily because the oil is not meeting as much restriction getting into areas it needs to get in to not anything to do with whether the oil is protecting as it should.

 

Cat actually told me 10W30 is recommended for the Acert year round.

 

Cat factory big wheels. There's a temp range (or there used to be)....

 

Who at Cat? I don't consider someone in a Cat shop being authoritative. You should be going by the Cat lube manual, and that alone. Most shops are not even up to speed on coolants let alone oils.

Just looking at a few Cat engine oil recommendation guides online myself and Cat says.....

CAT SEBU6251-13

Page 17 excerpts:
The proper oil viscosity grade is determined by
the minimum ambient temperature (the air in the immediate vicinity of the machine).\

Note: 10W-30 is the preferred viscosity grade when the ambient temperature is above −18° C (0° F) and below 40° C (104° F).

Read that as what most people will be operating in most of the time in the U.S. They go further to state that a 5w30 should be used below 0F. How many people stick to that recommendation from Cat? The only recommendation I see from anything I have found thus far that is direct OEM publication data, is that 40w oils are recommended if minimum ambient temps are going to be a minimum of 15F and up to 122F. Now, for those that start and operate their Cat motors in the winter, do you use a 5w30, 10w30 or 5w40 religiously according to Cat's own lube recommendations when the temps are going to be below +15F? And that is at engine startup! Yes, for the C-15. Looking at many oil brands, I see their 10w30 oils all meeting Cat ECF-3 specs.

Look, I have nothing against anyone using whatever they want. Heck, use a 50w oil it that trips your trigger. But it does nothing to support any argument that 10w30 is inadequate to use. Each person has to live within their own comfort zone. People have chided me over using a 10w30 in my JD zero turn riding lawn mower. They say a 40w should be used. Well, years and years of using it and it runs like a top. We have somehow been conditioned that thicker is better, and that is not always true. Find out what the OEM recommends from the OEM themselves and their manuals. Don't rely on word of mouth stuff which can be woefully wrong.

 

Full synthetic is just conventional oil with 13-20% synthetic additives, synthetic blends are 6%-12% synthetic additive to conventional oil. Synthetics do have better protection/lubrication at extreme temps though.(cold starts/high temps). When I was younger I was a mechanic,foreman always used the quote "Synthetics are like vitamins-If you eat a healthy diet, you don't need to eat vitamins. If you follow your maintenance schedule 99% of vehicles don't need synthetic, unless required by factory warranty".

 

Well, not quite true. It has nothing to do with additives, which are part of the additive package that handles the acids, detergents, extreme pressure modifiers, etc. It is the base oil itself. Full synthetic is synthetic base oil. Syn blends, you are somewhat right that there are a number of different percentages, depending on who is putting it together. The technical data sheets on the syn blend oil I use specifically states that it is 25% Group IV PAO synthetic and 75% Group II+ conventional. Unfortunately, many other brands are a little tight lipped about their percentages.

I agree, that most folks really will see nothing substantive from using full synthetic except their wallet is lighter. Proper maintenance and intervals go further to protecting components. And I agree also, for extremes like severe (and I do mean SEVERE) cold, synthetics have an distinct edge. But most of us do not operate out of Fairbanks, AK.