I have a 2004 Cat C-7 in a 36' Meridian which I have been using Rotella 15W-40 oil in it since new 68,000 miles back. Seems I remember reading somewhere the thought was that 10W-30 was better for the pumps and injectors.According to the Cat owners manual the 10W-30 is recommended up to 104 degrees ambiant temperatures, above that use 15W-40. Getting ready to change oil for the season (just sitting here in the house having cabin fever already with all this cold weather and nothing to do but think about what I could question) I called the Cat Help Line, told him what I had been using, that occasionally on our summer trips through Western Kansas in July temperatures have exceeded 104 degrees, and going over Colorado mountain passes every summer the engine temperatures will reach 210-218 for a short period, and we hardly ever travel in temperatures below 30-35 degrees.When I asked Cat's recommendation for oil viscosity use, he stated either one was fine, I could use either one with my usage, but would be no problem continuing with what I had been using. Was that to be expected, or just a wishy washy answer to keep me from trying to blame any unforeseen engine problems on the oil?What is the Forum's thoughts, especially anyone who has 100,000-200,000 miles on their engine with no pump or injector problems that might be related to the oil used? Don't want to start a hassle, just wanting to get some other ideas.

Wagonmaster2, First, we have a close sister ship to yours. Ours is an '04 Itasca Horizon, 36GD with the C-7 330HP CAT. The very short answer is, 10W-40 is the "norm" for those engines, based on general operating temps. On the CAT forum in the IRV2 Forums, the subject of protection of the "HEUI" pump has been discussed 'till way passed the cows coming home and, for the most part, it's 10W-40 that is the consensus. Our rig just turned 50K. I've been using Delo 400 10W-40 since we purchased the beast, about 30 months ago. I just changed it again. Man that stuff get's "BLACK" don't it? In all our fire trucks, we only used two weights of oil. For the two strokes, as in 8V-92 series Detroits, it was straight 40Wt. For all other engines, CATs, Detroit Series 60, and Cummins ISL, it was always 10W-40 Delo 400. I'm just about positive that 10W-30 will be just fine. You've been using it and nothing's grenaded yet has it? Scott

You can use Cat's DEO-ULS 5W-40 Synthetic which exceeds the performance requirements of Caterpillar ECF-3 (Engine Crankcase Fluid Specification), ECF-2, and the API CJ-4 category, if you want to use a synthetic. Mobil 1 Delvac 1 ESP 5W-40 meets the same specs and shows up in new oil analysis as almost identical.

Modern 4 stroke engines just aren't that sensitive to very small variations in oil rated viscosity. The difference between a CJ rated 10W-30 and a 15W-40 is very small, and many oils could probably be rated either way, since the window for the rating is fairly wide. If I wanted to put the best oil in, I would pick a synthetic 5W-40 like Rotella T6, unless I was running in very cold ambient temps when I would pick a 0W-40 full synthetic. With a HEUI injection system most times it's more critical to change the oil on time.Brian

It's going to be a long winter if 10 points difference concerns you. It's still November and you really do have cabin fever already.:B If you change every year then no reason to go synthetic.

Ivylog wrote:It's going to be a long winter if 10 points difference concerns you. It's still November and you really do have cabin fever already.:B If you change every year then no reason to go synthetic.But the diesel with 5W-40 synthetic turns much easier when it is down around 0° Fahrenheit than a diesel with 15W-40 dino oil. A diesel, because it has higher compression, is much harder to start in cold weather than a gas engine. When I leave out in February to go south, I want it to start without building a fire under it.

Cat C-7 diesel oil viscosity | Good Sam Community

wagonmaster2
Explorer
Nov 27, 2013
aztortuga wrote:
Has anyone considered rotella t5 a synthetic blend that one can get at walmart by the gallon and in 10-30 wt. I just changed oil and am going to try it out. Have been using delo 400 10-40 and rotella 10-40, but decided to try the t5 10-30 blend. I am not sure if there will be a discernible difference but will see. Its a little more expensive but with rebates not so much.

Seeing that WalMart started carrying Rotella SynBlend in 10W-30 was kind of what got me to asking the question of viscosity to begin with.
But after what Cat Help Line said about either 10W-30 or the 15W-40 I had been using was fine, and since I had heard for years it was best to stay with the same oil as Brett stated above I think I'll do just that with the Rotella 15W-40 I've used for almost 10 years.
aztortuga
Explorer
Nov 27, 2013
Has anyone considered rotella t5 a synthetic blend that one can get at walmart by the gallon and in 10-30 wt. I just changed oil and am going to try it out. Have been using delo 400 10-40 and rotella 10-40, but decided to try the t5 10-30 blend. I am not sure if there will be a discernible difference but will see. Its a little more expensive but with rebates not so much.
wolfe10
Explorer
Nov 27, 2013
Jeff,

My reasoning is that even though two oils may need the same mil-specs, they may do it with entirely different additive packages. Two engineers at different companies, give the same specs may come up with entirely different additives to meet that spec.

Could the additive packages be the same-- yes.
Could the additive package be different-- yes.
Are the two additive packages compatible-- MAYBE.

If you stick with the same oil, you KNOW the additive package is the same and there will be no issues. If you change oils, you ASSUME they are compatible.

Let me reverse the question: What would be the reason to jump from brand to brand?

BTW, this is much more critical with chassis grease than oil.
Spizzer
Explorer
Nov 27, 2013
wolfe10 wrote:
Jeff,

Were it me, first question is what oil has been used in the past.

If either Delo 400 15-40 or Shell Rotella T 15-40, THAT would be my choice.

If not, choose one and stick with it. I would not go synthetic, particularly if you are contemplating going back to dino.

I have used both over the years-- depending on what the previous owner used. Current coach Shell Rotella T 15-40. Last one Delo 400 15-40.

Boat Shell Rotella T 15-40 because it is available outside the U.S. where we take the boat.

Wolfe,

Can I ask what the reason to stick with the same oil is?

Jeff
Ivylog
Explorer III
Nov 27, 2013
Tinkerer, how often do you change the oil in your C7? Doubt it's once a year. 30+ years ago because of oil sampling I learned many "RECOMMENDATIONS" are expensive BS.
tinkerer
Explorer
Nov 27, 2013
Being a farmer we have Cenex 5W40 synthetic oil in bulk. On our equipment we did oil sampling and go 500 hours between changes without problems. At $17.00 a gallon it was no brainer to use it in my C7 Cat:)
wolfe10
Explorer
Nov 27, 2013
Always change oil when it is warm. Suggest at least 25 highway miles for full warm-up.

I usually change mine when we arrive home at the end of a trip-- couple of hundred miles on it that day-- good and warm.
wagonmaster2
Explorer
Nov 27, 2013
Thanks for all the input Guys. I think I feel better about just staying with the Rotella 15W-40 I've been using since the coach was new almost 10 years ago. I change the oil annually with usually less than 6,500-7,500 miles during that time.

And it really is amazing at how black how quick that new oil can get.

While we're on the oil change question, what is the feeling about warming up the engine just before draining the oil versus draining it cold after setting for a couple of weeks or so?

And Spizzer, be careful on your first oil change for your C-7. 19 quarts will put mine up to the full mark and no spew over the rear of the coach. I think some places were showing 22 quarts for the C-7 but was found to be too much.

And I didn't know the W after the first number stood for "winter", for some reason always thought it was for "weight".
wny_pat1
Explorer
Nov 27, 2013
wagonmaster2 wrote:
I think I know what 5W, 10W, and 15W would indicate as the first set of numbers in oil weight but what does 0W mean where the viscosity of oil is concerned?

The low-temperature viscosity (the first number, 5W in a 5W-30 oil, or 0W in 0W-30 oil) indicates how quickly an engine will crank in winter and how well the oil will flow to lubricate critical engine parts at low temperatures. The lower the number the more easily the engine will start in cold weather. Oh yes, the "W" in 0W or 15W stands for winter.
moisheh
Explorer
Nov 26, 2013
Fire Up: I think you meant 10/30 or 15/40. delo does not make a 10/40 The reason for the 10/30 recommendation ( according to jauston and others) is that the injectors use engine oil to operate. Apparently 10/30 will help with that system. As for finding someone with a C7 that has 200,000 miles without HEUI problems. GOOD LUCK. The C7 is not a good powerplant. The HEUI system is horrible. There are examples of people with less than 40,000 miles who have pump problems and the cost is many thousands of $$$. The problem is that very few entry level MGH's produced from 05 to 07 have anything other than a C7! Someone on IRV posted the latest oil requirements for cat engines. It states that 10/30 is preferred but 15/40 can be used. I called cat about 3 months ago and the tech said either is OK. I understand why some think the lighter oil will help with longer injector life but I am of the opinion that regardless of the oil used failure is inevitable. There is a small bonus using 10/30. Delo claims a 3.6% fuel mileage increase.

Moisheh

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