Pros and Cons of Synthetic Oil

[cburger]

I have been made aware of the Amsoil line of synthetic lubricants and have been contemplating the idea of switching over my Perkins 4.108 and gear to their products. Considering the motor was alwys run with traditional type motor oil was wondering if there are any benefits and potential negatives to this. The claims made on the Amsoil website are pretty dramatic as well as imput from frinds who love their products.

[neilpride]

Expect some low oil presure, some oil burning, if your perkins have lot of hours expect to some clacking noises, idk really , my 4236 run very nice in sae w40 , before i use a quality 15w40 , and i try for 2 oil changes with a sintetic, a mistake.

Your 4108 run forever with a quality 15w40 or in hot climates a 40w , idk the real benefit in a old iron , maybe because you can espace the oil changes intervals, for me not a good idea in a old engine.
Also remember that the 4018 have great clearances in pistons ,etc... a sintetic oil is like water, very thin....

[cburger]

Currently running Shell Rotella 15w-40, thought that was thin as water.

[AnchorageGuy]

Many of the older engines will run forever with traditional oil and will in fact develop problems after switching to synthetic. The synthetic is also much more expensive without any real benefits for your type of engine. Newer engines gain the most benefit. Chuck

[cburger]

Originally Posted by Waterwayguy

Many of the older engines will run forever with traditional oil and will in fact develop problems after switching to synthetic. The synthetic is also much more expensive without any real benefits for your type of engine. Newer engines gain the most benefit. Chuck

Kinda suspected this. I have been having a hard time finding any of the oil that is reccommended by specification in the Perkins engine manual, either MIL-L46152 or MIL-L-2104C . All the local outlets are selling the 15w-40 oils, an awful pat answer. When I ask for product that complies with these nomanclature numbers their eyes just glaze over

[hoolie]

Originally Posted by Waterwayguy

Many of the older engines will run forever with traditional oil and will in fact develop problems after switching to synthetic. The synthetic is also much more expensive without any real benefits for your type of engine. Newer engines gain the most benefit. Chuck

Absolutely right ! Synthetic oils are formulated for modern engines that run at high temperatures. For marine engines temperatures are much lower and the additives don't burn off as they should and cause problems. Stick with the type and grade(s) of oil recommended by your engine manufacturer!

[bstreep]

Originally Posted by Waterwayguy

Many of the older engines will run forever with traditional oil and will in fact develop problems after switching to synthetic. The synthetic is also much more expensive without any real benefits for your type of engine. Newer engines gain the most benefit. Chuck

I'm a classic car guy. I can't agree with the above - while it used to be true that early synthetics (like Mobil 1) were thinner than dino oil, that is no longer the case. It's now considered an "urban legend". A good synthetic (like Mobil 1) will perform just fine in an older engine.

HOWEVER, there's probably no real benefit. Unless you run your engine a LOT, you are probably changing oil based upon time rather than hours. In that case, a good dino oil is just fine, and synthetic is probably a waste of money. Trying to extend an oil change by time (once every two years versus once a year, for instance) by using synthetic is not a good idea.

Directly from Mobil's website:

Myth:Mobil 1 will leak out of the seals of older cars.Reality:






Mobil 1 does not cause leaks. In fact, new Mobil 1 was tested in dozens of industry standard and original equipment manufacturers (OEMs) tests to prove its seal performance. It is fully compatible with the elastomeric materials from which all automotive seals and gaskets are made. If an older engine is in good condition and does not have oil leaks, Mobil 1 provides the same advantages as when used in a new engine. ExxonMobil recommends taking measures to repair the leaks, then using Mobil 1. ExxonMobil also recommends following the automobile manufacturer's manual for the proper oil to use.

[AnchorageGuy]

There is quite a difference between the diesels in our boats and classic cars with gasoline engines so that may not be a good comparison. For the original poster, we ran 15W 30 in our 4-108 for 14 years and there were times when the engine ran for three days without shut down offshore. It was a happy engine. Chuck

[bstreep]

Originally Posted by Waterwayguy

There is quite a difference between the diesels in our boats and classic cars with gasoline engines so that may not be a good comparison. For the original poster, we ran 15W 30 in our 4-108 for 14 years and there were times when the engine ran for three days without shut down offshore. It was a happy engine. Chuck

My quote above this is from Mobil's website. Right below their Q & A involving synthetic for diesel - also OK.

[Dulcesuenos]

Sorry this is one of those dead horse arguments. Mobil 1 is a PAO PAO by nature reduce the lubricity of rubber shrinking seals, , extra Esters are added to counteract this effect. So you are half right half wrong. Synthetics due to their different molecular structure have a thinner basestock then conventional group I and II and III(synthdino) oils,. Also Synthetics do clean better and are able to carry stronger detergent and disspersant packages into areas that convetionals cannot. As a result if you had a major leak that has slowed over time due to sludge / grime build up, there is a good possibility that it will clean the area and renew the leak. More common on an old engine then a new. Also while the oil may have a higher oxidation and flash point preventing burnoff, it is more likely to leak past worn valve stem seals creating more consumption in a higher mileage neglected or worn engine.
We did experiment with our Westerbeke 27hp which calls for SAE 30 oil.
We ran a semisynthetic 10w30 and had 15 lbs less oil psi at the same rpm once warmed up. at idle it was closer to 20. switched back to the straight 30 again and regained our lost oil psi. You are right newer engine would see better benefit especialy in a turbo model. I'd run Rotella though due to higher Zinc and better ratings over Mobil.
In an old race car running a 355. we found the opposite true, The 8500rpms chewed up the conventional lowering oil psi once hot. The synthetic did not loose viscosity. Again big difference between High performance engines, and A low rpm marine diesel.

[Dulcesuenos]

Originally Posted by bstreep

My quote above this is from Mobil's website. Right below their Q & A involving synthetic for diesel - also OK.

And Mobil never lies? what about their claim to a 15k oil, oh yeah forget about all the exclusions for severe driving, planetary alignment, and cars under warr.

We should bring up anchors while were at it, hehe

[unbusted67]

I drove a boat with an Isuzu umbd61 350hp engine in it. It was a small passenger boat that ran a lot. The engine had appx 6000 hrs on it. We switched to the amsoil synthetic. Usually we would do an oil change every 250 hrs. With the synthetic stuff I started sending oil samples to the Caterpillar oil testing guys after 250 hrs every 100 hrs. at 600 hrs the guy told me to stop sending him samples because the oil was not showing any signs of degradation. He suggested I should change it at 750 simply due to the fact that it was getting dirty. That is a pretty serious improvement if you ask me. I would go with the synthetic stuff any time.

[sailstoo]

Originally Posted by Dulcesuenos

And Mobil never lies? what about their claim to a 15k oil, oh yeah forget about all the exclusions for severe driving, planetary alignment, and cars under warr.

We should bring up anchors while were at it, hehe

OR...
What do you think'd be better for a boat in "Pirate Country" (off the Jersey shore), a .308, a 12 gauge, or a 9mm?

[delmarrey]

It use to be, once you switched you couldn't go back. If you went back it would start to leak. Times have changed and the syn oil has improved.

>>>http://www.popularmechanics.com/cars...oducts/4213451

[Reefmagnet]

According to the handbook, my modern turbo diesel car must only use synthetic oil which is not surprising given the high stress operation and 12 months / 10000 km service intervals. Yet the Beta Marine handbook specifically advises against using synthetic oils in the Kubota bz482 engine which does surprise me as I've always assumed synthetic would be better in all cases except worn engines.