synthetic oil ?

[umblecumbuz]

Re: synthetic oil ?

Nevd said this: It is to stop this salt buildup that outboard manufacturers limit the thermostat temperatures to such a low figure

Unless I'm reading it wrong, Nevd is saying that manufacturers keep stats at low figures, because if they raised the stat opening temperature, salt deposits would seriously increase.<br /><br />But because ssea salt has such a flat solubility curve, you'd have to raise the motor temperature way way up before that started to happen, so IF manufacturers are deliberately putting in low temp stats, there has to be another reason.<br /><br />There are plenty of other salts present in water, each with a different solubility curve, but usually they are present only in minute quantities, and would not make any real difference to crud buildup.

 

[BillP]

Re: synthetic oil ?

The curve is flatish but salt still crystalizes more when temp is increased. It builds slower at 60C than 90C. Over the long term that may be the difference between clear passages or clogged passages. <br /><br />Look at t'stat temps for FWC marine engines VS RWC marine engines. FWC is higher...from the factory. Ask the mfg why...the answer is already posted.

 

[umblecumbuz]

Re: synthetic oil ?

Thanks for that info BillP.<br /><br />That's encouraged me to do some more research.

 

[umblecumbuz]

Re: synthetic oil ?

BillP,<br /><br />What I have found initially is this:<br /><br />Of all the common salts, Sodium Chloride (the salt we all boat in if we're in the sea) has by far the lowest increase in solubility with rising temperature. For example, at 90 degrees C there is a solubility increase of less than 5% over 60 degrees C. <br /><br />There are greater differences in salt density betweeen 100 yards offshore or half a mile offshore.<br /><br />This being so, I cannot accept the reasoning that stats are kept at 60 C rather than at 90 C to reduce the effects of corrosion. The difference in solubility is too small to have any noticeable effect on corrosion rates. <br /><br />Guess I'll keep looking for some other reason.

 

[BillP]

Re: synthetic oil ?

Originally posted by Stillfishing:<br /> BillP,<br /><br />What I have found initially is this:<br /><br />Of all the common salts, Sodium Chloride (the salt we all boat in if we're in the sea) has by far the lowest increase in solubility with rising temperature. For example, at 90 degrees C there is a solubility increase of less than 5% over 60 degrees C. <br /><br />There are greater differences in salt density betweeen 100 yards offshore or half a mile offshore.<br /><br />This being so, I cannot accept the reasoning that stats are kept at 60 C rather than at 90 C to reduce the effects of corrosion. The difference in solubility is too small to have any noticeable effect on corrosion rates. <br /><br />Guess I'll keep looking for some other reason.

No offense intended but what credible sources are you benchmarking that makes the following statment accurate? "The difference in solubility is too small to have any noticeable effect on corrosion rates". <br /><br />Here's some questions I would ask those sources...What reactions does salt have with other minerals in the water with aluminum? Are you considering that water temp is an average at the t'stat and there are probably hot spots in cooling passages that could make localized build up? If a motor runs 2000 hrs at 60C and then at 70C how much salt was deposited by each temperature? <br /><br />Hey, keep looking for facts and let us know.

 

[scotty c]

Re: synthetic oil ?

wow, things get out of control quick!<br />i was originally talking about crankcase oil<br />not lower unit.<br />anyway after checking the website, honda advises<br />that they based their testing on petroleum based oil, and and other product used must fall under the same standards.<br /><br />therefore, the safe thing to do is to run<br />5w-30 oil that they recommend.<br />

 

[umblecumbuz]

Re: synthetic oil ?

Woops! <br /><br />Sorry Scotty - I've hijacked your thread.<br /><br />Didn't mean to - one thing led to another.<br /><br />BillP has got me hooked on this salt thing, so I'll keep quite for a bit and do a lot more research. Maybe start a new thread if I find anything worthwhile.

 

[timmathis]

Re: synthetic oil ?

I got A kick out of it.