OEM engine design & oil recommendation question

[Ed_Flecko]

When an engine is designed by the factory and oil choices are chosen and recommended, do the engineers settle on a specific oil(s) due to its grade (weight), its characteristics, or a little of both?

I have a 2004 Toyota Tacoma with the 2.4 L 2RZ-FE motor and my manual calls for a 5W-30 "API grade SL Energy–Conserving or ILSAC multi-grade engine oil." On the theory that the factory recommended the grade they did based on the characteristics of a typical 5W-30 oil in 2004, I was wondering if those characteristics of that typical oil have changed over the last 13 years and if it's possible to, somehow, compare a 2004 5W-30 to a 2017 5W-30?

Thank you for your thoughts and feedback.

Ed

 

[Yah-Tah-Hey]

Current 5W-30 will work just fine in your 04. I have a 04 V6 Camry and have used the Mobil I 5W-30. Started using 0W-30 when it became available in our area some years ago.

 

[BrocLuno]

Oil selection is based on performance needs. Some engines are tough on oil as in higher heat and more shear. Others less so.

Then the lawyers and the bean counters get into the act. The OEM's all supply oils under their name brands and they are all contracted with refiners. So you tell me, is it a compromise...

I'd be on forums related to that specific vehicle and engine and see what has been working well? Also look at UOA's from that engine. It will soon be apparent what works, and what does not...

 

[09_GXP]

Typically something like fluid requirements are determined well before the first prototype is built. These requirements typically come from an overall corporate strategy such as using one fluid in every vehicle. This is combined with the other requirements; power, reliability, NVH, etc... At this point you have a "value package" that engineering signs off that they can meet. Then the work starts on how to design and build and engine that can meet the agreed upon requirements.

Of course, there are always exceptions but this is the way most engineering development will go.

 

[Mitch Alsup]

Originally Posted By: Ed_Flecko
When an engine is designed by the factory and oil choices are chosen and recommended, do the engineers settle on a specific oil(s) due to its grade (weight), its characteristics, or a little of both?


Nothing (absolutely nothing) is done by oil grade--it is done by viscosity and temperature.
However, a lot of the recommendations are finalized by an oil company sponsoring the first fill oil of an engine.

Engine engineers choose a specific viscosity at a temperature somewhat above the water thermostatic temperature. Based on the chosen viscosity, crankshaft bearing clearances are decided, cam lobe widths are decided, cam follower loads are determined, and the piston ring package determined; somewhere along the line the valve guide clearance is also chosen.

Once the operating conditions are satisfied, the cold start viscosity is determined. Remember, the engine wants is designed viscosity from the startup onward--and every oil is too thick at startup. What we want is an oil that flows at low pressures to get to the points needing lubrication before the oil film left from the previous run is scrapped away.

There are 3 basic operating viscosities the engine engineers choose from: 7 cST (xxW-20), 10 cST (xxW-30), and 14 cST (xxW-40).

Thin oil viscosity choice needs thinner crankshaft bearing clearances to properly support the loads under pressure (that is more precise machining of the block and crankshafts), but these oils clean and lubricate the ring package better giving more freedom in ring package choices and cylinder wall finishes, however thin oils almost require rollerized cam mechanism (which most cars have these days).

 

[Camprunner]

What about motors that come out recommendeding a range of oil change options based on tempeture say 5w30 below zero and 10w30 or 10w40 in warmer climates and then that same motor 5 or 10 years later recommends only 5w30 for all tempetures? For ex 2005 Nissan VQ40DE had a range of oil weight options then several years later inc today 5w30 only for the entire range?

 

[willistheguy]

My roommate and I have gotten into arguments about this topic. We both have freshly rebuilt small block fords and go back and fourth between what the engineers originally recommended and what they now recommend.

Many years ago Ford had a TSB that said all their vehicles that originally required 10w30 will now be switched to 5w30 because "5w30 provides optimum protection and an increase in fuel economy".

Years later there was another TSB that stated many of their vehicles that originally required 5w30 will now be switched to 5w20 because "5w20 is an improved formulation to improve fuel economy and it has been determined that it can be used in vehicles previously recommending 5w30".

Some vehicles are on both lists, some are not. But for the ones that are, that means that Ford recommended 10w-30 originally and then 5w20 now.

So I wonder about a few things. My hope is that ,yes, those vehicles were designed around the oils readily available at the time, but when oil technology improved they decided the engines would fair better with these newer oils. My fear is that they switched the vehicles over because these grades are mostly the same and it is easier for them to just store 2 grades at the dealership and say to the customers that it is because they're improved.

I am not trying to hijack this thread with a Ford topic. I was under the impression that oil grades don't really change over the years, BUT, their may be better grade options for your vehicle over time since oil technology can make those more affordable. Meaning that what the manufacturer said originally may not always still be the best choice.

 

[Garak]

In addition to what you mentioned, note that there are some changes within grades over the years. Note that the PCMO 10w-30 grade (in North American guise) evolved over the years, with HTHS dropping as EC and RC requirements came into effect, leaving obvious additive package changes aside.

 

[y_p_w]

Any engine of course has to be tolerant of a wide range of motor oil characteristics. The owner's manual for my 2004 WRX stated 3 different multigrade (5W-30, 10W-30, 10W-40) oil types for normal operation in my climate (temperate) as well as optional high temperature and/or towing use with 30 wt, 40 wt, 20W-40, or 20W-50. I'm pretty sure that some people substituted any number of different oil weights without the engine blowing up. I've used 0W-40, which is actually recommended by some motor oil companies for this car. I think some have tried a 15W-40 HD diesel oil if it had a gasoline rating. The factory fill was supposed to be some special breakin formula 5W-40.

The basic idea of oil weight is kind of a blunt tool since it's only where the oil starts, and not where it is after the components break down. An engine should be able to survive on almost anything within reason. I even remember hearing one guy suggest that perhaps a straight 30 wt and a block heater would be ideal for protection where a 10W-30 or 5W-30 is recommended by the manufacturer.