Is high HTHS still important for a normal vehicle?
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I think its more:
If its adequate its adequate.. More than that and a slight reserve is not necessary.
if it is not adequate you have extra wear which usually wont show up for a period of time.
There is no general rule that doesnt have exceptions however.
It is usually better to err on the side of higher HTHS.. because higher you just lose a tiny fraction of MPG and an unnoticeably small amount of performance..
Too low can cause permanent damage or excessive wear.
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Are not the oil specs recommended by the engine manufacture cover the minimum HTHS? Ed
No. Today's oils are not more robust and there is no magic additive or remarkable base stock that suddenly performs the job better. What has happened is that the better manufacturers are changing the way engines are built to accommodate today's oils. Pistons have skirt coatings, rings are wear resistant, cams no longer use flat tappets, adequate roller bearings (cough-cough) in followers and lifters are used by the better makes, cam chain pins now can be sourced with micro coatings that prevent rapid wear and so on, cam chain tensioners are configured to accommodate normal wear, variable cam timing can adjust accordingly, and so on.
It is true that AN base stock is a good lubricant, and is said to require a bit less in the way of anti wear additives. As long as extreme cold weather performance is not a factor.
A good example of modern design: A coated piston, where the rod bearing is made larger to carry the load of a boosted engine, utilizing 0W-20 oil with an HTHS of 2.3. The rod cap won't fit down the bore if configured conventionally. Adequate? In the short term, yes. Few of these Jaguar AJ engines last a long time though. Ford uses a nearly identical design in their 2.7L Ecoboost, with 5w-30 oil, the result is considerably better.
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4WD
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Yes - GDI came out to help our 20k lubes reach 7k before it’s thinned by fuel …
Only if you want some added engine wear protection due to the viscosity MOFT factor. A xW-30 will typically give you HTHS viscosity of around 3.2-3.5 cP. Better protection IMO (some headroom over "adequate") than using an oil with HTHS of 2.3-2.6 cP (typical xW-20) ... especially in a GDI engine that can fuel dilute the oil and decrease the HTHS viscosity even more.
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Yes it will. Physics is physics.
But the engine may wear excessively or perhaps fail depending on how low the HT/HS.
HTHS > Fuel economy any day of the week. I am willing to take a 0.5%-3% drop in overall fuel economy if it means my engine stays protected.
I am not a fan of CAFE standards. Example is my mom's Rav4, uses 0W20 but it is under warranty so I am stuck. Good reports on 0w20 oils but I need my peace of mind. Once warranty is done, I will bump the oil up to a 0W30 or a 5W30.
I am not a fan of CAFE standards. Example is my mom's Rav4, uses 0W20 but it is under warranty so I am stuck. Good reports on 0w20 oils but I need my peace of mind. Once warranty is done, I will bump the oil up to a 0W30 or a 5W30.
The other thing too though is you can find XX-20 oils with a 3.0+ HTHS so switching to a -30 isn't always necessary.
No way, never knew this. I'm planning on using the Pennzoil 0w20, you think it would be 3.0 in HTHS ratings?
Doubt it, and Pennzoil doesn't publish HTHS info ... you'd have to contact them to see if they will divulge that info. You'd probably have to go with a xW-30 to get 3.0 HTHS or higher.
But at the same time no warranty is determinate on a grade. Grades are recommendations. The warranty coverage is predicated on engine damage.
I will get in trouble for saying this, if you drive your car reasonable then maybe it does not matter, but if you drive the car unreasonable then maybe a high HTHS is better. 4 me I will drive my car reasonable and use an oil that has a high HTHS for the added protection or just to give me a feeling that I am using an oil almost as good as an oil sold by HPL or Redline.
It comes down to your driving/use - I would wager 90%+ of BITOG is not using their vehicle(s) in a way that running an oil to get a higher-than-OE-recommended HTHS would make any meaningful difference in their ownership tenure w/r to wear etc. etc. EVEN IF it does provide better protection.
My impression is that most engines fail due to their inherent fatal design flaws much more than wear related mechanisms. Well, probably second most common to people literally not checking oil and starvation. The engine teardown YouTube channels are full of engines that were run almost dry.
Like ZeeOSix pointed out, most likely not. It would be an oil from someone like HPL with their No VII Euro 5W-20.
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I like running a bit higher HTHS oil in the Subaru as it can run as low as 1100 rpm while accelerating gently around town, and it spends a lot of time at 1600rpm on the highway, so XW30 put my low rpm worries to rest.
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