Great Read Regarding Oil Choice!

[shawnhayes]

I disagree (as if anyone really cared) with some of the premises in that treatise.

Especially the 3,000-5,000 mile recommendation. That may be too early. There is some data to support that the best synthetics are formulated to optimize wear in the middle portion of the oils lifespan, which may be later than this (this also found on bobistheoilguy).

However, the best advice is of course above: Follow the manual.

And, to add the best quote I've ever heard, when used to apply to modern API SN certified oils, is:

Originally Posted by Sellout

Unbiased hard data is hard to come by for a couple reasons. One is that this is the internet and unbiased data will get drowned by 1000 opinions you didn't want.

Another is that a truly unbiased opinion would say something like, "it doesn't matter. they're all good enough for what you're doing", but NOBODY wants to hear that.

Everyone wants to believe that there is an engine oil available here in the US that will cause mechanical failure and then choose not to buy that one. But that oil does not exist.

No greater quote ever heard about modern oils. Ever.

Shawn

[bluesubie]

Originally Posted by shawnhayes

There is some data to support that the best synthetics are formulated to optimize wear in the middle portion of the oils lifespan, which may be later than this (this also found on bobistheoilguy).

Some info here:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1528239

I believe there have been some manufacturer papers on this as well in regards to Passenger Car Motor Oils.

Of course, those that are preaching to follow the manual, I presume that you also kept the factory fill in as long as the manual specifies correct?

-Dennis

[mav1178]

Originally Posted by shawnhayes

No greater quote ever heard about modern oils. Ever.

Yup... my goal for used oil analysis is to retain proof of worthiness of engine condition and monitor/check for problems before they get out of hand. As long as it's the proper grade oil for my temp range and intended use, I'm good.

-alex

[bluesubie]

And here's a good thread about higher oil temps with thicker oils.

http://www.bobistheoilguy.com/forums...Number=3108659

-Dennis

[Suberman]

Originally Posted by bluesubie

And here's a good thread about higher oil temps with thicker oils.

http://www.bobistheoilguy.com/forums...Number=3108659

-Dennis

Yes, the higher viscosity oil runs slightly more slowly through the bearings picking up more heat. Not good. You might think that "cooling" the bearing more is a good thing but bearings are metal and heat isn't an issue until it causes such high temperatures in the oil that the oil film starts to break down. More useful than an oil pressure gauge on a modern engine is an oil temperature gauge. When single grade oils were used oil pressure correlated usefully to oil temperature leading lay people to think pressure was important. Oil temperature is the vital information a racing driver needs.

The post about positive displacement oil pumps, implying the flow rate doesn't change with viscosity, forgets that the oil pump can deliver much more oil than is needed, that's what creates the pressure, and supercharger air pumps do the same. Excess volume passes through the bypass which triggers the low oil pressure switch to indicate enough pressure exists (amazingly low oil pressure is the minimum needed).

[Admiral Ballsy]

Originally Posted by Suberman

Yes, the higher viscosity oil runs slightly more slowly through the bearings picking up more heat.

Slower picks up less heat. Each unit mass of oil will rise higher in temperature, but there are less unit masses passing over the material to be cooled, per unit time.

Faster-moving coolants remove more heat, all else equal.

[Suberman]

Originally Posted by Admiral Ballsy

Slower picks up less heat. Each unit mass of oil will rise higher in temperature, but there are less unit masses passing over the material to be cooled, per unit time.

Faster-moving coolants remove more heat, all else equal.

You got the concept backwards my friend. You don't want the oil to get hotter per unit volume. Thinner oil moves faster and removes more heat from the bearing area while remaining cooler itself, less heat per unit volume.

Radiator cooled fluids are a different matter. You want the highest temperature coolant you can run while still keeping the engine cool enough. Thermostats reduce coolant flow rates for this reason.

Oil isn't primarily there to cool a street engine.

[FRSRAVEN]

I just posted some repeat information in another thread (didn't see this one until just now). People might disagree, and on BITOG some certainly do, but here is my opinion on the subject.

Bitog is a wealth of information. Most of which is constantly repeated as people ask the same questions over and over.

IMO, the practice I follow, and one already mentioned by other members here and in AE Haas's article, is to pick the thinnest oil you can get away with based on the temperature you are likely to encounter. Or another way of looking at it, pick the oil that will keep you within your desired viscosity grade at the target temperature you will experience.

For a street driven car, that is usually whatever is recommended in the owners manual. For a track driven car, it could be something completely different. I certainly would not want to be running a 20 grade oil at 250 degrees or higher on the track, especially a super high VI 0w-20 like Toyota's synthetic. (I'm referring to the FA20 engine at this point).

So if I'm going to experience 250 degree oil temperatures, I should 1. install an oil cooler, or if not possible, 2. use whatever grade of oil gets me to my target viscosity. Probably xx-30, with a stout additive package.

Viscosity is only one metric, especially when referring to cSt. If I'm going to be tracking my car, I'll be mainly looking at HTHS, as some would argue that is a more relevant means of assessing viscosity as it is experienced by the engine.

AE Haas was famous for running a 5w-20 in his wife's Murcielago. He used a 5w-40 in his personal Enzo. Both of which specified 10w-60 IIRC. His reasoning, which I agree with, was that as daily driven vehicles his oil temperatures never reached the levels necessary to prompt the use of a 60 grade oil. He kept track of both vehicles using used oil analysis, and noted good results with his oil choices. I think he eventually was driven off BITOG for a time, but I don't read BITOG daily anymore, so I'm unsure of his current posting habits. What I will say is that he was a plastic surgeon, and engine oil was a hobby of his. He was not an engineer. For the sake of disclosure.

For a daily driven FR-S/BRZ, there are very few bad choices among API certified oils.

[Admiral Ballsy]

Originally Posted by Suberman

You got the concept backwards my friend. You don't want the oil to get hotter per unit volume. Thinner oil moves faster and removes more heat from the bearing area while remaining cooler itself, less heat per unit volume.

Well, which is it? Is it what you said first - that

the higher viscosity oil runs slightly more slowly through the bearings picking up more heat

No, of course it isn't. And to your credit, you disagree with yourself.

Originally Posted by Suberman

Radiator cooled fluids are a different matter. You want the highest temperature coolant you can run while still keeping the engine cool enough. Thermostats reduce coolant flow rates for this reason.

Thermostats set the minimum steady-state temperature of the coolant, and attempt to regulate said temperature through permitting heat exchange through the radiator, not through regulating fluid velocity.

[Suberman]

Originally Posted by Admiral Ballsy

Well, which is it? Is it what you said first - that

No, of course it isn't. And to your credit, you disagree with yourself.



Thermostats set the minimum steady-state temperature of the coolant, and attempt to regulate said temperature through permitting heat exchange through the radiator, not through regulating fluid velocity.

You seem to be unable to understand the difference between heat and temperature. Get those two concepts clear in your mind and report back.

Wikipedia isn't the place to get this info but try starting here:

http://coolcosmos.ipac.caltech.edu/c...al/differ.html

I mean fluid velocity in cooling systems is proportional to water pump rpm but it doesn't have be, it's just easier. My point was you want hot coolant for efficient cooling. You want cool oil to protect the integrity of the oil film. Slower speed through the bearings gets up THAT oil while it is in the bearing. It doesn't matter how hot the oil gets after it passes put if the bearing. But "hot oil" within the bearing and total heat contained in a given volume of oil flowing into the sump are not the same thing at all.

[viscositosis.rex]

You can use Sustina 0W20, High-Moly Mazda 0W20, or Toyota Genuine 0W20, the three lighest oils on the market, for 5,000 miles, with track days, as a base line. I would have Dyson analyze the oil before going any further. The newest polymers perform amazingly well. They have smaller particle size, better molecular structure and can be used in smaller quantities when the finished product is made. When conducting analysis especially note the HTHS and flash point numbers to ensure that fuel dilution does not prevent you from having adequate viscosity at operating temperature. it is time for people to get over their thin oil anxiety, a driver is only cheating himself out of performance. Clowns will clown. Haters will hate. This is the up to date truth about motor oil. Dennis knows who I am.

[fstlane]

Originally Posted by viscositosis.rex

You can use Sustina 0W20, High-Moly Mazda 0W20, or Toyota Genuine 0W20, the three lighest oils on the market, for 5,000 miles, with track days, as a base line.

This is sound advice. I actually just picked up a case from the local Mazda dealership at $7.00 per quart.

[Suberman]

If you are still worried that the 20 weight oil is too thin try and find out what F1 engines run for summer driving at 18,000 rpm. I guarantee you will be surprised.

[rice_classic]

Originally Posted by Suberman

If you are still worried that the 20 weight oil is too thin try and find out what F1 engines run for summer driving at 18,000 rpm. I guarantee you will be surprised.

or ALMS cars or NASCARs and so on a so forth. Street engine =/= race only engine as their range of purposes differ and thus from a concept to design to implementation and function their lubrication needs also differ.

The F1 engines have to be preheated before they're even turned over. They're wound so tight that they cannot turn over while cold (according to Steve Matchett).

But anyway... it's still a going point nonetheless I just figure it's worth it to anyone taking the point or making the point to include the reality of the 2 types of engines as well.


Edit: I've experienced a phenomenon on the race car, now running a thinner oil (but have oil cooler) where the temp will rise and peak during a race at 260F then subsequently drop back down to 240F and remain there for the rest of the race. I didn't believe it when I read it on BITOG where the increase of "flow" as the oil heats and thins will increase the oil's capacity to cool itself and that what I experienced might happen. Well it does.

doubled edit: I'm getting something wrong describing the phenomenon, perhaps someone can explain what's exactly happening in technical terms better or more accurately.