In truth, I once heard it described that a diesel truck running on vegetable oil smells like a big french fry going down the road.

Mmmmmm.

 

Muffler bearings were fine, but the blinker valve kept sticking. So I lube it up with ear wax, that does the trick.

 

Stick with 5W30, and if your changing it often as you should the cheap stuff is fine, and cheap filters. Sure ideally a 0W30 full TRUE synthetic with a zinc additive and a pricey low micron filter with a drainback valve is better. But that's money often better off used elsewhere. The only reason to use "high milage" oils is if you wanna be lazy about your oil changes, but they still aren't that much better. DO NOT use a 10W40 unless you have oil pressure problems from wear.

Personally I lied about the bacon grease, I use 5W40 Rotella T6 Synthetic on my high mile 460 and change it when it looks bad or my 300 needs oil, it gets the old oil from my 460 . But I have a slight oil pressure issue, hence 40 otherwise the rest is a matter of bang for the buck, it's a good oil for the money.

The old ladies car gets 0W30 Mobil 1 at 5000 intervals, had it sence almost new, and plan to have it around for a looonngg time, and at 115k now the engine is still like new.

 

Hey Opossum, why is this? Is this because the bad rap 10W40 got from all of the GM products (camshafts, I believe) failing in the early 80's which they blamed on 10W40 instead of admitting crappy QC and material selection, or is there another reason for your statement?

I'm truly curious as myself and many others use 10W40. We all have our oil preferences and I'm not trying to start a battle, I just wouldn't mind more information as to why you stated this.

 

Two main reasons the engine is designed for 30, and flow is more important then film thickness.

It's much more important that all the oil that can gets in all the places it can get as much and as quickly as possible, most of all at startup. Something like 95% of wear is at startup, ANY small amount of time removed from getting the oil where it needs to be is a VERY good thing. That and with a thicker oil then you need all your doing is creating drag and heat from pumping it around. Yes 40 can be good in a hot loose engine, I use it in my 460 as stated.

BUT it's the 10W that really kills ya, W doesn't stand for weight, it stands for Winter, which is silly, should be C for cold but ohh well I didn't create the standards. It's based on the viscosity of the oil at a cold temp, the other number is at a hot temp 210F. I can't remember the low temp. So the higher the W number the longer it takes to get oil to where it needs to be at startup. So why aren't all oils OW you ask, well that comes from the characteristics of dino oil, regular 30 weight oil if it had a W number would be 30W30 to make a 5W or 10W they add viscosity modifyers to the oil to change it's temperature charactaristics. These additives however are bad for the oils ability to lube and last as a whole so it's a trade off between faster oiling at startup and better oiling when warm and oil longevity. What they do to make a 10W40 is take a 10 weight oil and add enough stuff to it to make it act like a 40 when hot. The downside to this is that these additives break down, so as the oil breaks down it becomes a 10W30 then a 10W20, and eventually just a 10. Ohh and as they break down they become sludge, it's not the oil that actually breaks down it's the additives.

This of course is dino oils, synthetics are another critter, synthetics do this naturally without the additves. So a synthetic can have a big spread like 0W50 without being full of all these viscosity modifyers. So while you'd have a really hard time finding a 0W30 dino oil, and such a oil would suck, 0W30 synthetic is all good and easy. So why aren't all synthetics 0W whatever, simple answer they have to sell the stuff and people think a 5W or 10W is better. Ohh and why don't I use a 0W40 then, money, the 5W40 I use is pretty cost effective and is a deisel oil meaning it has more additives that will help my older engine live. To use a 0W40 I'd have to pay way more and to me more cash for other things and frequent changes are more important then $8/qt oil. If I had serious money in this engine or planned to keep it a long time you could bet your bottom dollar I'd have a fantastic oil in it, likely a Redline or Amsoil product. Ohh and an accumulater, which frankly I should put on anyway, just hasn't found it's way to the top of the list yet.

So you put all this together with the fact that synthetics are much slipperier anyway the ideal is a OW30 synthetic. True sythetic(type IV), few that are called synthetic really are(type III) and there are several kinds but that's another topic. But that stuff is pricey and a 5W30 dino is just fine for the OPs engine. Synthetics do have 2 downsides comapred to dino oils to. The main one is that the actual molecule is MUCH smaller so they tend to leak more, they are however less flamable so they don't burn off the cylinder walls as much. Second they can lube too well, yes too well. The piston rings need a little drag or they can do whats called flutter which can cause them to shatter. Second on a new engine or new parts some things need to wear in, synthetics can prevent that. I had an engine shatter it's piston rings shortly after I switched to synthetic, it does happen. This engine however I found out when I took it apart had been "rebuilt" but the old pistons reused making the ring lands worn, and the clearance from piston too cylinder wall to large.

So anyway, why not a 10W40, cause others are better, the only place a 10W40 belongs is in an engine that was either designed for 40 or has oil pressure problems with a 30 from wear, excessive heat, or you don't intend to change it often and isn't worth putting synthetics in. Ohhh and all this 0W stuff, we really need a new standard, what's next -5W? that's silly and what does 0W mean anyway, it's really just them saying it's thinner then a 5W when cold, but can't really be 0.

 

Excellent response and explanation; thank you! + Reputation given appropriately.

 

So if I follow that right, then I should be running thinner oil than 15w40 in my Powerstroke as it has a fresh motor with tight clearances.

But I use the same 15w40 in the 82 with the well worn 351W. Hmmm.

One other thought. Oil has two main purposes. Lubrication obviously, and removal of heat. A thicker oil will provide a better "cushion" in the bearing area, but with the rotational forces, heat builds fast. If the oil can't be replaced fast enough, the bearing will overheat and seize/spin. Thinner oils will carry the heat away faster as they will move through the bearing area faster, but usually at a lower pressure. Those thinner oils may not have enough "cushion" to prevent bearing contact(the reason for thicker oils in a diesel with high compression and high bearing loads). Hence the reason for additives to provide a wider range of characteristics for a given oil. The additives are not just for heat ranges, but pressure loading also.

 

Uhm yes, yeah, right, you betcha, sort of. Powerstrokes are WAAAAYYYY oil sensitive but I'm sure you know that. And the thinner then 15W40 thing is a yes and a BIG NO, certainly NOT anything lower then a 40, it was designed for 40, it needs it. But sure IF synthetic and ONLY IF synthetic then a lower W number would be a good thing.

The 351, hey whatever floats your boat, your wearing it out faster then you need to but it's old already and if ya got the 15W40 use it. Personally depending on the 351 I think a good bang for the buck would be to get a GOOD synthetic NON-API oil like an Amsoil 0 or 5W40 for the PS, and when the PS is done with it put it in the 351 by then it's alot like a normal 5W30.

 

I get the 15w40 by the case or by the drum, so I usually have a lot of it here. The 82 doesn't seem to mind.

How am I wearing it out faster?

 

Cause as I said before the 15W part, it's much thicker then it needs to be when cold so it's taking longer to get where it's needed during cold start, wearing it out.

 

I'm going to have to disagree with oppossum here.


DO NOT use 5W30 above 60 degrees F in any engine built before 1990, or any engine built with clearances and tolerances that match engines built before 1990. Always follow the owners manual recommendations.

Newer modern built engines have closer tolerances, therfore they can use 5w30 and 0w30 fine. The older engines such as in our vehicles are a lot "looser" and their tolerances are no where near as tight. Infact the tolerances on a severly worn modern engine would be like a brand new rebuild for one of our era engines by comparison.

10w-40 is the thinest oil Ford recommends driving above 90 degrees F in temperature.

10w30 is only good for between -10F through 90 degrees.

5w30 is only good for 60F and below...


You don't want to hear my comment on that practice.

I'm wondering why you have pressure issues. Perhaps it's the starting wear from using too light an oil? Using too light an oil for start up is just as bad as using too thick. (explained further down)

Your wife's car from the mid 90's or newer by chance?

It's equally important on our older engines... (explanation farther below)

What you say is mostly correct, but you are leaving out two important factors. Temperature and tolerance/clearances.

5w-30 is great for our engines below 60F degrees because of what you typed above. What happens when it's 90F degrees outside is that the 5W-30 oil is not thick enough to cushion the internal parts inside the engine. Using too thin of an oil will cause metal to metal wear on engines, specifically the bearings at start up. Using too thick will do what you described immediately above.

Why it's so important to factor in temperature, and OEM tolerance and clearaces when changing oil viscocity.

I run 15W-40 most of the time, and when it gets colder I run 10W-40.

I do not run 10w-30 anymore in the winter like I did a decade ago because of wear on my engine. 700,000+ miles...

You can use thiner oil, but you will do damage to your engines, unless the temperature outside warrants the thinner oil.

You are correct sir...

What opposum doesn't seem to understand is our engines were designed for 10w-30 or 10w-40 oil at certain temperature ranges, and 5w-30 and 5w-20 at other temperature ranges.

Using a 5w-30 engine oil at 90+ degrees will alow metal to metal contact of the bearings at startup. Using a 10W-40 at -20 degrees will not let the oil flow and will cause dry starting. Both are equally bad for the engine.

Our engines are not like modern engines with roller bearing camshafts, and super tight computer measured clearances..

My advice, use the owners manual recomendations on viscocity, and look at the temperature you are planing on driving in.

 

in many cases, the manual will have a chart showing the acceptable temperature ranges for the different weights of oil. it isn't rocket science, and close does count.

on a honda i worked on recently, running a heavier oil was very problematic with the hydraulic variable cam timing actuator. it could handle nothing heavier than 5w30.
but obviously that doesn't apply to any of our engines.

in an old 300 of unknown mileage, i ran 20w50 plus a bottle of STP to keep it from rattling. after a year or two of this, i finally got around to diagnosing and replacing the stuck lifters, and went back to running 10w40.

 

Of course you do.

Guys I don't care to argue, take my advice, don't take it, I don't care if your engine doesn't last as long as it could. I just felt like helping others understand. Re-read what he said with several facts in mind; that engine temps are regulated and rather consistant once running, that he makes no mention that the ratings are at different temps and standard, that at 210F there is NO differnce in viscosity between a 0W40 and a 15W40, the number before the W is at 0deg F and the number after is at 210deg F, the effect of friction modifyers and the differences in dino and syntheitc as noted.

Sure outside temps matter, most of all at startup and sure if it's really REALLY hot where you live when your starting your engine or if dino oil and you intend to go a while between changes, then yeah a higher W number has a place. And sure if really hot or cold and your engine can't keep it's oil temp stable then a different second number has it's place. But all you have to do is look for yourself to see the truth. Compare the thickness(viscosity) of your oil when you drain it from a hot engine with it's viscosity when you poor in fresh stuff at outside(starting) temps. It's thicker isn't it, ideally your oil never needs to be any thicker then it is when drained hot, even when cold. So the ideal oil is one that is the same viscosity at both temps.

So re-read what he just said, and ask yourself if this makes any sence or is he arguing just to argue.

I suppose I'll address a little of what he said, for kicks and clarity.

IDK why so specific on 90, nothing changed in 90 to affect any of this. For the most part, BUT it doesn't consider everthing and isn't up to date on modern oil tech. LMAO ONLY he says, cause that is such a narrow range of temps. The world we live in is never somewhere between -10 and 90 outside, geez. Hey we do agree on something My oil pressure dipped just a little too low when really hot and at a low idle. Sure it's from wear, likely both at the bearings and in the oil pump. Why, idk, I got it in 2007, it was already 20 years old, I have no idea the actual milage and it wasn't all that well taken care of at that point. I have no idea what previous owners had put in it. Maybe 15W40, the guy I got it from did mostly have diesels, I have no way of knowing. What I do know is it's worn pretty bad, had so much blowby when I bought it that it blew about 3qts all over the traffic behind me during the 15 mile trip home . And when I got it really hot with 5W30 in it the oil pressure was too low at my nice low in gear idle. Well sure, but in the real world with real oil that you can really buy this doesn't really happen. 90s wow 115k would be low miles, no it's a 2001 Maxima. And before you start, 5W30 is the manufacture recomended oil. 10W30 if warm enough and ya want. But no reason to do that unless using dino oil and want to go a while between changes, neither of which I do. For most of it's life it's had Mobil 1 5W30 in it, but when I found their 0W30 for the same cost I switched to it. It also has redline synthetic ATF in it and other then a small mod to the front axle/wheel/brakes for safety is stock and been 100% trouble free except for the axle thing and a wiring harness plug that liked to come just loose enough to throw a code. I left out MANY factors like kinematic viscosity, centipoise viscosity, centistoke viscosity, viscosity breakdown, shear viscosity, how it's measured, that it's far from exact, that even with dino oils where the crude comes from matters, , that 0W and 5W weren't technically grades until 1999, etc. this is a post on a forum not a research paper on oil.

 

Seems like you want arguments, Opossum.

 

I like dispelling incorrect information, it helps me as much as everyone else for everyone to have more correct info. Like if more people understood that modern 0W syntheitcs are better then more people would buy them, more manufactures would make them, and the price would go down while availabilty goes up. This is even more true for the FAKE synthetics, that aren't really synthetics and most of the market don't know they are getting swindled. If these went away or were even labeled correctly the price and availablity of true synthetics would be SOOOO much better.

That and I'll admit I do at times like arguing it makes you learn both were your wrong and where you need to know more. I did look up and learn more info cause of this discussion and I might be changing some of my practices. That said you can't use logic and reason against an illogical mind making an unreasonable argument, so often it's of no use.