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Changing oil in diesels

Old 05-07-2006, 01:07 PM
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Default Changing oil in diesels

If the manufacturer says change every 50 hours, is it wise or hurting anythng gong to every 25 hours, or less. Or am I just wasting my time and money. I read someplace that not getting the oil hot enough or used enough could further damage the diesel engine. Didnt make any sense but just wanted to hear from you guys thanks Jeff
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Old 05-07-2006, 01:15 PM
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Default Re: Changing oil in diesels

The only diesels I've worked with have been continuous duty Cats and Cummins on the oilfield boats.
I'm not an expert but I'd stick with the manufacturers guidelines. Don't see where it would hurt to change every 25 hours but if they recomend 50 hours go with that.
The fuel filters are critical so stay on top of those as well.
My 2 cents....probably not even worth that.
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Old 05-07-2006, 02:18 PM
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Default Re: Changing oil in diesels

JnT is absolutely right. It is very important to keep filters clean on big diesels. And not only fuel and oil filters but air filters as well. As far as changing oil is concerned, no need to do it more often than 50 hours. As a matter of fact, 50 hours is overkill. On Seateks which are about as fragile as a diesel is going to get, every 100 hours is fine.

Jeff, you mention oil temperature and it is absolutely true that diesels must be properly warmed up before going up in revs. Just like any other engine really but because diesels have this reputation of strength and reliability, people sometimes forget that it is still an engine and that it will break down if you don't treat it right. After running hard for an extended period, be sure to let it idle for a while and let it cool off gradually. This will dramatically extend the life of your turbos.

Check your injectors regularly. If one cylinder is not functioning properly, you can do serious damage to the engine. The catch is that on a diesel, you don't notice this as easily as on a gas engine. It may go completely unnoticed at cruise speeds. If during acceleration you think you see even a wee bit more smoke than usual or if you think that maybe you felt an unusual vibration, don't think twice: check all your injectors.
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Old 05-07-2006, 04:18 PM
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Default Re: Changing oil in diesels

Thanks guys, apprieciate the info, I just dont want to do anything wrong, and just enjoy boating the end of the year with out anything to much to worry about. Jeff
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Old 05-07-2006, 06:45 PM
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Arrow Re: Changing oil in diesels

Though not marine specific the following info may be helpful:

Sixty-thousand (60,000) mile diesel oil change intervals have been successfully achieved in fleet operation using Amsoil synthetic based oils. Amsoil has produced premium, synthetic based API approved diesel engine oils since 1972. Present fleet tests of 90,000 mile drain intervals have found the oil free and clean of deposits and suitable for continued use. Amsoil claims a four to eight percent increase in fuel economy when using their product. They are saying to extend 2-3x and change the filter inbetween "manufacturer's recommendations" and "top-off". Easy and savess lot of $$$.

Mack Truck has recently approved 25,000 mile crankcase drain intervals, up from 15,000 and 20,000 mile intervals formerly recommended. These increased intervals are effective for most 1990 and later model vehicles used under on-highway conditions. These are a part of the "new breed," lower emission engines currently in production. Other manufacturers, Detroit Diesel, Cummins, and Caterpillar, have also increased their recommended drain intervals. These changes are based on using new API CF4 rated oil. Oil that meets this standard is necessary for these new engines to meet desired operational, emission, and longevity standards. Many diesel engine oil experts forecast that in the near future diesel oils (CG) will be classed as diesel only. Many current multi-viscosity oils are classified SE/SF/CF. This "wide spectrum" oil may be used in gasoline or diesel engines. Diesel only oils will carry no "S" classification. Oil consumption and crankcase contamination are reduced by using a newly designed upper piston and piston ring. Reduced blow-by gases reduce crankcase contamination. Higher reach upper rings and oils containing greater dispersants reduce oil consumption
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Old 05-08-2006, 11:54 AM
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Default Re: Changing oil in diesels

Good idea would be to get an oil analysis done at various intervals to see what is going on in the engine. The report ususally comes back with a recommended change interval.
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