Extending The Life Of Your Oil

Professional Skipper Magazine Issue 41 Sep/Oct 2004 (unedited)

 

During one of the many boat shows I met a skipper who owned a gray boat, which he worked out of a town down on the east coast of the Coromandel. The engine had just been rebuilt. In fact by the sounds of it, it was almost a completely new engine, as the block, cams, shafts and pistons were all replaced.

Along with the oil analysis programmes, which we were advertising at the show we were trying to highlight the benefits of fully synthetic diesel engine oil as an option over the more commonly used mineral oils. This option gives the engine/vessel operator a number of advantages namely improved protection of the moving parts, extended engine life, better fuel economy and longer drain periods. This longer drain period interested the skipper as he was sick of doing oil changes every couple of hundred hours, not to mention having to get rid of the waste oil. He said if he could reduce the amount of time spent doing this he would be a happy man.

Now extended oil drain intervals are all well and good, however if you do not know what is going on internally in your engine then they can be very dangerous, thus the use of a good oil analysis programme is essential. Virtually all manufactures will not recommend extended oil drain periods unless oil analysis is carried out. By doing this at the end of your oil drain interval i.e. just before the next oil change you can see not only how the engine is wearing but also the condition of the oil. If the oil is full of contaminates i.e. Water, Soot, Sodium and/or Fuel Dilution then the extended oil drain intervals may have to wait. To get the best out of your new synthetic oil you will need to sort these issues out first. However, if the oil analysis results show up a good clean set of figures then changing over to fully synthetic oil should not be a problem. One thing of note is that you should check to see if your engine is compatible with the new oil. Older engines don't tend to be and certainly 2-stoke Detroit Diesels and Gardners are not, however most late model high performance engines are.

The skipper decided to make the change. His newly rebuilt engine had had an oil change done with only 50 hrs on the clock and had since done just over 200 hrs, so another oil change was in the offing. I was keen to help with the change and the opportunity to take a sample from the old oil. So with the wife in tow and the new synthetic oil in the boot we headed out of Auckland for a weekend away down on the Coromandel.

When we arrived it was an absolute wonderfully clear mid winter's day. The skipper said lets take her for a rip so as to warm up the engine. It was like a milk pond as we headed out of the harbour and south along the coast to Hahai, wow the wife was most impressed. Once we were back though it was all hands to the pumps. First with my trusty vacuum pump I removed a sample of oil then the skipper got going with the sump pump and removed the 30 Ltrs or so from the engine. After which, we replaced the filters and introduced the new synthetic oil. Then it was off for a beer and a relax for the rest of the weekend before heading back to the big smoke.

About 10 weeks later I heard from the skipper. His oil service hours were just coming up on 250 so it was time to take the first sample to see what was happening to the new oil. I sent down a kit so that the skipper could take the sample. Once the results were back I was able to lay them against the original ones from the sample I had taken when I was down there. The original set showed low metal counts and a good clean set of results as far as the oil condition and contamination levels go. When we laid the next set beside them you could see a marked increase in most of the wear-metal counts, however all were still within acceptable limits.

This increase is very common when changing over from a mineral oil to a fully synthetic one. It is due to the increased levels of detergents in the synthetic oil which tend to clean the engine out better than their old mineral counterparts. Normally we find that it's best to do the first oil change for the new oil at about the same time as the old one then move on to the extended oil service intervals after that. This is so that any remaining residue from the old mineral oil can be removed and diluted out of the system for good.

Again about 10 weeks later I sent down another sample kit. This time the results came back perfect with very low wear-metal counts and contamination levels. The oil's quality reserves (remaining additive levels) were still very high, while the acid build-up in the oil was minimal, thus the oil was very capable of further service. The instruction was to carry on and to give me a call when the oil had done 500 hrs, to which he did. Again the results were similar to the last set, however this time the oil quality reserves were a little lower. This tends to indicate that the quality of the oil is starting to drop off and that the oil will need to be changed in the near future. We agreed that he should do another 100 hrs then draw another sample (just to confirm) then drop the oil and replace it. The last oil analysis confirmed everything was alright and that the new synthetic oil was capable of over 600 hrs in his engine. During the next oil service interval we took two samples, one at 300 hrs and the other just before he changed the oil. All in all a happy skipper, less oil changes, better protection for his engine and we think better fuel economy.

Good Sailing
Written By Kelvin Hieatt
Managing Director Marine Diagnostics Ltd

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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