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Old 30-09-2012, 06:24   #1
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Perkins 4.108 synthetic oil?

I'm about to change the engine oil on the Perkins 4.108 diesel engine in my sailboat. The boat is new to me as of August 1, 2012. The PO had changed the oil just prior to selling me the boat. This is the first oil change since I bought the boat. I'm inclined to put in 5w-40 synthetic oil, as I generally like synthetic oil properties. The oil used previously in this motor has been non-synthetic 15w-40 oil. The motor has 2,500 hours on it and runs excellent. The oil pressure has always been around 40 to 60 lbs. I believe this oil meets the Perkins manual requirements. Is this a good oil selection for an engine with these hours that has not previously had synthetic oil?

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Old 30-09-2012, 06:51   #2
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Re: Perkins 4.108 synthetic oil?

There is no scientific data to support the idea that mixing mineral and synthetic oils will damage your engine (as long as it meets the same American Petroleum Institute (API) and Society of Automotive Engineers (SAE) specifications as regular oil)
When switching from a mineral oil to a synthetic, or vice versa, you will potentially leave a small amount of residual oil in the engine. That's perfectly okay because synthetic oil and mineral-based motor oil are, for the most part, compatible with each other. (The exception is pure synthetics. Polyglycols don't mix with normal mineral oils.)
There is also no problem with switching back and forth between synthetic and mineral based oils. In fact, people who are "in the know" and who operate engines in areas where temperature fluctuations can be especially extreme, switch from mineral oil to synthetic oil for the colder months. They then switch back to mineral oil during the warmer months.
There was a time, years ago, when switching between synthetic oils and mineral oils was not recommended if you had used one product or the other for a long period of time. People experienced problems with seals leaking and high oil consumption but changes in additive chemistry and seal material have taken care of those issues. And that's an important caveat. New seal technology is great, but if you're still driving around in a car from the 80's with its original seals, then this argument becomes a bit of a moot point - your seals are still going to be subject to the old leakage problems no matter what newfangled additives the oil companies are putting in their products.

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Old 30-09-2012, 07:12   #3
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If your talking about the Shell Rotella T6 full synthetic 5w40. That is the best diesel oil made. Less viscosity shear than any other diesel oil made in that vis range. Should have great results. Keep us posted! Most engine manufacturers know less about correct lubricants than those in the lubricant industry. By 2014 every new diesel truck in the usa will be factory fill required full synthetic. The benefits of synthetics are huge less heat cool quicker better fuel economy cleaner w less deposit s and cleans pistons better. 5w40 exceeds all 15w40 requirements
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Old 30-09-2012, 07:13   #4
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Re: Perkins 4.108 synthetic oil?

If you are switching to synthetic, stick with the same weight. However, I would have second thoughts about switching to synthetics on a Perkins 4.108. Perkins does not recommend synthetic oils. This has been confirmed by Trans Atlantic Diesel, British Marine, and S&W Diesel -- all of whom are Perkins dealers and have extensive experience with this particular engine.

I am using Delo 15-40 oil and will continue to do so due to its well established track record of excellent performance on this engine. If something is not broken, why attempt to fix it? Just my two cents...

Also, this would be the perfect time to get an oil analysis. You put enough hours on it for the analysis to show data that would be useful for you to better understand your engine's overall health.
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Old 30-09-2012, 07:26   #5
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Re: Perkins 4.108 synthetic oil?

I had my engine rebuilt in 08 and after putting on about 200 hrs on regular oil 10-40 switched to synthetic. I did it this way to let everything seat. I now have over 400 hrs on it and am very pleased with it. I will run it about 300 hrs before changing it but will change the filter about every 50-100 hrs.I always change it when the boat goes on the hard for the winter. The engine does push a little. It did ease up when I went to 10-40. about 6 ozs every 25 hrs maybe I didn't run it long enough to seat everything. Doesn't sound like much but when the engine only holds about 94 ozs it gets topped off. Use it in the transmission also, along with cars lawn mower anything that needs oil. Don't know why someone would swith back in summer as it was made for jet engines just because of the heat.
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Old 30-09-2012, 14:02   #6
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Re: Perkins 4.108 synthetic oil?

Thanks everyone for the replies. Astral Blue - I didn't know about the caution on using synthetic oil on Perkins engines. I will think again on this and just stick to the dino oil, as I'm not having any issues with it. Why mess with a good thing, eh?

Thanks again all.

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