which is the better lube straight or multi-weight ?

All other factors the same. Which motor oil generally provides the best lubrication?

Eg. Pennzoil conventional 10W-30 vs Pennzoil conventional sae 30.
Or Shell Rotella T1 straight weight in applications where it meets spec?

http://www-static.shell.com/static/can-en/downloads/products_services/lubricants/rotella/rotella_t1.pdf

Or of course Amsoil Sae 30 synthetic vs. it's own Series 3000 5W-30 or HD 15W-40 ?

http://www.amsoil.com/a/Synthetic-Diesel-Motor-Oil-Engine-Oil

In theory the multi-weight, but a lot of us hard headed old timers have a problem accepting that

Because of where you and me live, I put multiweight in everything used all year long. Except like a summer only push mower, 30, for a snowblower, 20. But since we aren't blessed with a constant temperature, and I don't change oils 4 times a year, I don't bother with the 1920's rules. Well, unless you concider the 11 months of winter like we been having lately.

Straight if you never let it cool off. Multi if you let the machine sit overnight or longer. Temps below freezing etc. The most wear on an engine is in the first few min. of starting til the oil gets warm.

The OP manual for the 1480 IH diesel combine with 436 or 466 engine states that #30 is perfered and they recommend oil change at 200 hrs.
In the early / mid 80's IH said 15-40 was OK in those engines as long as you changed it at 100 hrs.
Said the reason was that the IH cam lobe and lifter design would slowly destroy the viscosity improvers in the multi viscosity oil.

Otherwise, less cold start wear should happen with a multi vis oil in an engine designed for it.

Hello buickanddeere,
My vote is for Mobil 1.
It is the choice of many automobile manufacturer. 40+ new vehicles are filled at the factory's assembly line with Mobil 1.
Multi grade is also my choice for better, or at least more convinient lubrication.

Guido.

That question cannot be logically answered as asked. What type of engine? What type of service? At what temperature ranges? Flat tappets or roller tapppets (makes a big difference).

Considering this is an "old" tractor forum, let's consider oil for probably 99% of the tractor engines dicussed here, along with stationary engines.

If some chump goes to his local auto-parts store to get multi-visc motor oil - it is MOST likely that oil will not have the proper lube requirements. Especially for engines that do not have roller-tappets on the camshafts. That goes for the cams that operate the valves and also the cams inside in-line fuel injection pumps. Gas engine motor-oil formulated since 2009 has lowered the anti-wear additives that older equipment needs. And, it's not going to tell you that on the label.

Now - if you buy racing oil, or tractor oil, or most diesel oils - you'll be okay for your gas and diesel engine tractors. Even the "Traveller" brand sold at Tractor Supply and made by Warren Oil has a high level of anti-wear additves.

Chances are if you go down to NAPA and buy 30W, you'll get some sort of off-road of diesel rated oil. But, if you ask for a multi-viscosity, you'll likely get a highway gas-engine oil that does NOT have the proper protection.

Shell Rotella T straight-grade 30W and 40W has an excellent flash point, good level of ZDDP, and a high HTHS (high temp-high shear) rating.

To the other extreme, if you insist on using only one grade of oil regardless if 105 F or 25 below F - then any multi-oil is better then any single-grade 30W or 40W . That because of the damage you can do during cold starts.

I don't know of any auto/truck or tractor manufacturers that recommend straight weight oil anymore. As far as synthetic is concerned, my 2011 truck maintenance guide specifies 5000 mile oil changes w/filter when using conventional oil and 10000 mile oil/filter changes when using synthetic unless E85 is used more than 50% of the time. Then cut those above numbers in half for both conventional and synthetic. I'm sure BMW has done a lot of research on this and has a wealth of information. Is it accessible? Here's a new one, to me. Tractor manufactureres are pushing their own oil now because they say the traditional thinking, which has been pretty much to use oil recommended for trucks, i.e; Rotella, etc., is not valid because tractors use approximately 75% of their available engine power most of the time whereas trucks use less than 40%. Is this a valid assumption? Are their oils any better? They say they have been developed exclusively for farm tractor use. I just bought a new 125 HP tractor and intend to use the manufactureres oil. Why? For one thing, it costs about the same as Rotella or Delo.

An acquaintance of mine ( a liscensed diesel mechanic) worked in the Esso/Exon lubricant lab in Sarnia Ontario in the late '80s. early '90s. They used 6V92 Detroits as their test engines. Engines were hooked to dynos, run wide open and lugged down to about 1400 rpm and run for 100 hrs, tore down, wear measured and then rebuilt before the next test, I questioned him about how much wear would be evident in that short a test period but he assured me lots. He said at that time there was no multiweights equal to a straight weight. Undoubtedly, there have been improvements in multiweights, particularly synthetics in the 20 years since then.

Glen, all other factors being equal, I wouldn't use Pennzoil in my lawn mower.. I have been around too many engines that didn't like it at all. Mike

That's a good question for which I do NOT have an educated or scientific answer. One could argue using straight grades of oil such as SAE20, 30, 40, 50 when and wear necessary, under the right temperatures, which WOULD require changing oils more often, which most people would not, at times including myself. One could then argue maufacturer suggested specifications, which these days are generally multigrades, possibly based upon scientific knowledge, improved technologies, or experience, or a knowledge that most have gotten lazy, so multigrades are the lessor evil to meet minimum requirements. One can never got wrong by following manufactrer suggested specifications, and that being said, I have in my fleet of vehicles that include two Cummins Dodges, that I follow manufacturer specs on, tractors and other equipments that I follow manufacturer specs on, also a Buick Century and Jeep Cherokee that the manufacturers suggest using regular unleaded gasoline in, but I have always and will always use premium unleaded, the same as my Allis Chalmers B lawn mower. The Deeres, the Massey, and the Case are all diesel, and other than fuel additives, get what are manufacturer suggested specs.

Your wallet and your equipment, good luck.

Mark

Those same tests have been done more recently and yielded the same results.

Agree with you, wouldn't use it to lube the manure spreader chain, did a lots of O H last 40 years on Pennz run engines, sludge in a can!! But must be better now, I see it advertized more now, hasn't been around for years.

Like most folks I use multigrade oils for convenience, especially in vintage tractors that are used little and changed only yearly.

Multigrade oil was developed for this very reason - convenience.

Excepting special circumstances, I would use straight weight oils if operating a self-owned fleet that I planned to keep for awhile.

Dean

There have been some charts on the forum that show that the cold pour point of Shell Rotella 15/40 is the same as 30 weight oil.I put some rotella in my tractor and pick up in December.When I started the pick up the oil pressure was all over the gauge.Seem to have trouble picking up the oil,never saw that in the truck but noticed it often in hi milage engines after an oil and filter change.Many years ago I was putting the top on a transmission in a cold garage.I kept a jar of 40 weight oil to smear on gaskets.I stuck a screwdriver into the jar to pick up some oil,The screwdriver stood up in the oil and left a hole when I pulled it out.I still wonder if an oil pump could have pulled that oil thru a screen on a cold start up.I put some Chevron 10/30 and a new filter in the truck this time.Its hard to say one brand of oil is better than another because a lot of it is bottled in the same place.My father in law had an oil truck during the 30s.He sold kerosene for 8 cents a gallon.He sold motor oil in 2 and 5 gallon cans There were special oils for Fordson tractors.Oil had different prices and names.He went to get a load of kerosene and motor oil.He went into the office to place his order.No one in the office at lunch time.He went into the warehouse and saw all the cans lined up near a spigot.The single pipe went up to an oil tanker on the RR track.A hose connected the tanker to the pipe.It was obvious that all the cans were filled with the same oil and sold at different prices.

Here is a truthful story about a straight weight episode. I recently changed the oil in my Jeep Cherokee. I always run a Castrol 30 w, nothing else. I use it in the Impala and the GMC that I bought new in 2006 and 2004 respectively. After changing the oil and the filter, I later headed out to diner in the Jeep. About 5 miles down the road I noticed that I had no oil pressure. I stopped, opened the hood and saw nothing wrong. I then restarted the engine and since I heard no noises, I continued down the road. I assumed that the oil pressure gauge had gone bad or that I had an electrical problem. About 5 miles later the engine began making some awful nosies and I knew it was indeed an oil problem. The old filter gasket stayed on the engine and I had tightened the new filter up and crushed the old gasket in ahead of the new filter.
I removed the gasket, retightened the filter, added 5 qts of oil and then restarted the engine. It made a little nosie and smoothed right out. That happened about 10K miles ago and it has been running fine since then. My point is that oils today coat metal so well that straight weights are perfectly acceptable. Heck multigrade , additised oils didn't really appear until the 60's. We used base oils in the old tractors, cars and trucks for years. I think multi grade oils have a place in extreme temperature scenarios, but straight weights work just as well.

My $.02 cents worth.

Had a gasket stay on the block on my chevy truck but I started the engine to check for leaks.I had one.My Ford truck has the filter base in a place you cant see so I take a close look at the old filter.Ive always looked for missing gaskets on filter changes but missed that one.I found the oil pressure came up fast with 10/30 not like the 15/40 Rotella that had the oil gauge bobbing around.Ill stick to 10/30 in the truck.