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Old 07-10-2019, 10:32 AM   #81
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Ah, the definitionof 'synthetic' is tricky, I'll come back to that. However, from a practical standpoint 'synthetic' lubricants use high viscosity index (VI) base oils. Conventional base oil has a VI of around 100, high VI is anything more than 120. As I said in my other post, VI is a measure of the change in viscosity with temperature, a higher VI changes less with temperature i.e, thins less when hot, thickens less when cold.

When synthetics first started entering the mainstream (e.g. Mobil1) they used something call polyalphaolifin (PAO) and a small amout of various esters. PAO is an oligimerization (just combining) of decene (C10 hydrocarbon) into higher molecular weight molecules to achieve the desired viscosity. Esters cover a wide range of materials but can be used to adjust the properties of the PAO. However, as base oil technology has advanced, there are now many sources of high VI base oil manufactured using hydrocracking targeting 120+VI.

Shell has a unique position though, they built a big natural gas to liquids plant in Quatar that makes base oil from natural gas using the old Fisher Tropsch technology (invented by the Germans in the 1920's and used in WWII to make fuel from natural gas). This base oil is in the range of 140 VI, very similar to PAO in VI. It's really quite a good base oil (no I'm not a 'plant' from Shell), it doesn't need any adjusting fluid,is less expensive than PAO, and actually I think performs better. PAO is used in some applications mainly due to its superior ultra low temperature flow capability.

Now back to the he formal definition of synthetic: it is that the molecules comprising the base oil are artificially made (synthesized) rather than being a distillation product of crude oil. Many years ago when synthetics started, all base oils were distillation products of some type. However, today, almost all base oil, 'conventional' or 'synthetic' are actually synthesized via hydrocracking and isomerization (i.e. break down the molecules and build them up with the properties you want). The only difference is the VI targeted in manufacturing. These base oils have no sulfur (which was a residual of distillation) and are very 'pure', they appear almostwater white before additives are added (additives tend to be darker). So by the formal definition of syntetic, every quart of oil you buy for your car could be called synthetic. Chevron alludes to this by saying it contains 'Isosyn', they were the leader in this change to synthesized 'conventional' base oil. By the way, these base oils ARE better than the old distilled ones.

So, synthetic is really a marketing definition these days and by no means are all of them the same. But keep in mind 'synthetic' base oil doesn't impart any miraculous properties, claims of 'molecular bonding' and 'stronger films' are mainly clever marketing. The wear, oxidation, corrosion, and deposit control of modern engine oils today is carried by the additive package. A combination of anywhere from 5 to 15+ descrete chemical compounds added to the base oil to meet the performance requirments.

The last question is what are these oils based on instead of oil. Well as I said, Shell uses natural gas. Almost all of the other fluids are derived from crude oil by one route or another, even PAO.
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Old 07-10-2019, 12:53 PM   #82
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Slomo, thanks for that! Confirms a lot of my experience with lube oils.

Retired engineer here too. One of my first professional experiences with the world of oil was when I had to make a hydraulically operated machine I designed work in a -40F ice cream freezer warehouse. That's when I learned about 5606 grade aviation hydraulic fluid and how it had been deep dewaxed with extra steps in the refining process for cold service in airplanes at altitude. Got the machine to work with that, no way it would run with conventional 10 weight hyd oil.

Lately, I have synthesized Golden Ale and Czech Pils from water, malt and grain. It is a fine lubricant for mind & body. Keep that thought should you wander north this summer, my boat (& malted beverage lube) is kept in La Conner.
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Old 07-10-2019, 01:55 PM   #83
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Slomo,
If I was to get a jug of Mobile 1 w/o any viscosity improver added what would be it’s viscosity?
I have been getting 5-30 Mobile for my Avalon car at the dealer to take advantage of his bulk oil prices. I can’t buy oil at his retail price to me.. the’ve been putting 5-30 in my car. With MV range that wide I assumed it was synthetic ... but I learn it’s not even a blend.

My engine has well over 250hp and I drive moderately hence low engine loads and temps so I’m not feeling the need for synthetic. That said what lube oils are available w less VI .. or none at all? If I can find oil suitable for my car w far less VI I’ll start changing my oil again.

Lastly beyond more frequent changes what can I do to minimize sludge buildup?

HaHa I was just in the auto parts store and see adv. syn. 10-30 for 9.99 qt.
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Old 07-10-2019, 07:15 PM   #84
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Quote:
Originally Posted by GoneFarrell View Post
Slomo, thanks for that! Confirms a lot of my experience with lube oils.

Retired engineer here too. One of my first professional experiences with the world of oil was when I had to make a hydraulically operated machine I designed work in a -40F ice cream freezer warehouse. That's when I learned about 5606 grade aviation hydraulic fluid and how it had been deep dewaxed with extra steps in the refining process for cold service in airplanes at altitude. Got the machine to work with that, no way it would run with conventional 10 weight hyd oil.

Lately, I have synthesized Golden Ale and Czech Pils from water, malt and grain. It is a fine lubricant for mind & body. Keep that thought should you wander north this summer, my boat (& malted beverage lube) is kept in La Conner.
Sounds good! We store in Anacortes (on the hard). Planning a trip in a few weeks. Still sorting things on the Tollycraft so doing a couple shorter trips this summer (did one in June).
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Old 07-10-2019, 07:51 PM   #85
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Slomo,
If I was to get a jug of Mobile 1 w/o any viscosity improver added what would be its viscosity?
I have been getting 5-30 Mobile for my Avalon car at the dealer to take advantage of his bulk oil prices. I cant buy oil at his retail price to me.. theve been putting 5-30 in my car. With MV range that wide I assumed it was synthetic ... but I learn its not even a blend.

My engine has well over 250hp and I drive moderately hence low engine loads and temps so Im not feeling the need for synthetic. That said what lube oils are available w less VI .. or none at all? If I can find oil suitable for my car w far less VI Ill start changing my oil again.

Lastly beyond more frequent changes what can I do to minimize sludge buildup?

HaHa I was just in the auto parts store and see adv. syn. 10-30 for 9.99 qt.
Most 5W30 are conventional, but I wouldn't worry about it. They all use Group II base oils (hydrocracked, isomerized, isodewaxed). Modern ILSAC GF5/API SN oils have quite a bit of dispersant, detergent, and antioxidant in them. They're very robust. Even synthetic oils use viscosity modifier (VM), just a bit less. But with the additive systems in these oils the difference in VM level isn't important in real world driving.

Doesn't your Avalon specify 5w-20 engine oil? If so I'd use that. If the engine is designed for 5W20 there's no added protection with a 5W30. I know people back up at the low viscosity but really its OK. Make sure you use an ILSAC GF5 / API SN oil from a major supplier like Pennzoil (Shell), Chevron, Mobil, etc. Unless your engine specifies synthetic, or you start doing cold starts in North Dakota in the winter, synthetic won't offer and real benefit.

Sludge: Sludge is a result of short trip low temperature driving i.e. 2-3 mile trips where the oil never gets warm enough to drive off the condensation. Modern oils have a lot of sludge protection. However, if you drive only short trips, then shorten your oil change interval. Normally most of us drive long enough to heat the oil and drive off moisure at least once a week.
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Old 07-10-2019, 08:32 PM   #86
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Thanks much for your response and help.

I almost always drive 30 miles after a startup. So not a sludge problem by your input and I’m going w it.

Re the 5-20 you’re probably right for the Avalon. I don’t ever pull a trailer or go up a mountain pass in 90+ heat either.

And the 10-30 “Advanced” full synthetic is only $29 for 5 quarts at the Irish auto parts store.

Thanks
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