Need help and opinions on diesel engine oils

[RalphVa]

I have been using Conoco T5X Heavy Duty SAE 30 weight diesel engine oil for the past ten years, and to be perfectly honest have had no problems. But now my drum is empty and I have a decision to make. I was running this oil in an old dump truck with a gas engine, and an older tractor with a diesel engine in it that I hardly ever used it in the winter time. Now I have picked up a Kubota with a diesel engine that I will be running in the winter time. I see Rotella offers a 15W-40 that maybe an option. The Conoco and the Rotella are "conventional" oils. No synthetic base in them. Everyone I know seems to think the synthetic blends are the way to go (the wave of the future, I'm old fashion). Now here's my question,,, the Kubota calls for 10W-30, would running the 15W-40 have any detrimental effect on the engine especially in the winter time? Would it be fine to use this grade of oil? I'm thinking the 15W-40 would be better than running the straight 30 weight in it. I also think that if you change your oil and filters regularly you don't need synthetic, or do you think I should switch over to a synthetic or a synthetic blend? You guys have any experience along these lines I sure would like to hear them. Do you have any favorite oils that you prefer over others? Thanks in advance. RRM

Think 10w30 is just plain old 30w but in new format.

I'm using 5w30 in all my diesels (JD 2025 and Isuzu generator) because it is what VW speced for our 2010 VW TDI and used at 10k changes through to 7th year when we sold it back to VW. In fact, I'm still buying the Castrol 5w30 (probably hydrocracked synthetic) that VW sells.

For all my water cooled gasoline engines (3 of them), I'm using M1 0w20. For my air cooled lawn mowers (JD and Honda walkbehinds), I use M1 5w40.

Could use 5w30 in everything, but get fuel economy improvements using the 0w20.

My VW Cabrio I had before the current convertible had horrid hydraulic valve knock on startup with anything but 0w30 (should have started using 0w20 then in it).

The oil pump simply picks up the 0wxx oil instantaneously, even down to -40 F/C. It'll make your valve train more happy in years to come.

Don't believe any of those ASTM bar charts that show maximums for various oil grades. They don't make sense unless they'll telling you what to use in air cooled engines. 0w20 is good for even racing conditions. In fact, formula 1 racer use 5 and 10w oils. It's to give them use at full rpm even when cold and at the really high revs these engines run.

Ralph

 

[Olympus]

The only thing that synthetic offers over conventional is longer service intervals, any other advertised benefits are just smoke and mirrors really. But synthetic does make some people feel all "warm and fuzzy" inside, so more power to them. I actually run Amsoil synthetic products in my ATV, UTV, and zero-turn mower. I figure I'm using them a lot harder than anything else and I plan on keeping all of them for a long time, so why not spend a little more for a "better" oil. It probably doesn't offer me much over a conventional though.

Single-weight oils are really a thing of the past. I see absolutely no reason to use a single weight oil for anything relatively modern.

15w-40 is kind of the "standard" weight for most diesel engines. If you live in or operate a lot in cold weather climates, then 5w-40 would be a better choice. I personally would not chose 10w30 for a diesel. I run 15w-40 in my LS tractor, but I keep it stored in a heated shop year round. The coldest temp my tractor would ever start in is 40F, which is where I set my thermostat when I'm not working in my shop. If I was starting the tractor in any temps colder than that, I would opt for the 5w-40.

 

[Oldoak]

Amazing how many people know more than the tractor manufactures and oil producers and don't consider what the operator manuals recommend good enough. However, like has already been said "whatever makes you feel warm and fuzzy".

 

[Olympus]

Amazing how many people know more than the tractor manufactures and oil producers and don't consider what the operator manuals recommend good enough. However, like has already been said "whatever makes you feel warm and fuzzy".

Oil isn’t a “one size fits all” kinda thing. The guy in northern Minnesota probably shouldn’t use the same weight oil as the guy in south Texas.

 

[Rustyiron]

Oil isn’t a “one size fits all” kinda thing. The guy in northern Minnesota probably shouldn’t use the same weight oil as the guy in south Texas.

.......That and I took the OPs main question as wondering about running synthetic vs dinosaur oil.
I don't buy the extended change period without additional oil filtering, particularly in a diesel.

 

[Olympus]

.......That and I took the OPs main question as wondering about running synthetic vs dinosaur oil.
I don't buy the extended change period without additional oil filtering, particularly in a diesel.

I don’t know about diesels, but a lot of guys have shared oil analysis results with their gas engine vehicles using synthetic oil and the same filter for extended service intervals and the results are very impressive. Most are using a higher quality filter though. It’s certainly true that synthetic oils are capable of longer service intervals with gas engines, that’s already been proven. I haven’t researched the Diesel engine results though. But I don’t run synthetic in my tractor, so it hasn’t been important enough to me. At every 100 hours, my machine doesn’t see any hard use or high temps to justify the need to switch to synthetics. Maybe if a machine was used in operation for a business where down time costs money, maybe the longer service intervals would pay off. But not for this homeowner.

 

[coupman35]

Like this topic am in northern Ontario Canada and winter are cold -30 and -40 at some time .So am looking for oil for that weather I have a b2650 Kubota and they recommend 10w30 oil , just woundering if I go whit 15w40 is that good or not.

 

[Olympus]

Like this topic am in northern Ontario Canada and winter are cold -30 and -40 at some time .So am looking for oil for that weather I have a b2650 Kubota and they recommend 10w30 oil , just woundering if I go whit 15w40 is that good or not.

If you’re in cold climates, you want a LOWER first number. The lower the first number, the thinner the oil at colder temps. Thinner oil will flow faster and start lubricating quicker in colder temps. I would highly recommend a 5w or even a 0w. I would NOT recommend a 15w oil for your situation.

 

[DEWFPO]

Like this topic am in northern Ontario Canada and winter are cold -30 and -40 at some time .So am looking for oil for that weather I have a b2650 Kubota and they recommend 10w30 oil , just woundering if I go whit 15w40 is that good or not.

For your conditions I would not use a 15W oil unless the equipment was kept in a heated building all the time. At those temps, a 0W would work much better for you if the equipment is truly 'cold' started.

DEWFPO

 

[marchanna]

Yup. 0W40 full synthetic for northern Ontario.