Engines that actually require Thick or Thin oil?

[nap]

Originally Posted By: Donald
Before you can run thicker oil than is listed in the owner's manual, one should be required to submit evidence in the form of plastigauge measurement of bearing clearance from all main bearings.


Before continuing the "thick oils won't fit through the tight clearances of modern engines" argument, one should submit plastigauge measurements showing what these clearances actually are.

 

[tomcat27]

The bearing clearances on my SBF are .0035, so I suppose I need to run a thicker oil. I'm using 20w50

 

[billt460]

I think it comes down to two trains of thought. The first is if you believe the trend to thinner oils is because of, 1.) CAFE mileage demands?... Or 2.) Tighter engine tolerances and clearances? And the other is if you believe that thicker oils offer that much better "protection" to begin with?

Hard to say either way when you have modern cars today easily going well over 200,000 miles on the much thinner oils. Then there are the oils themselves. How much better are they, then back when 10W-40 was considered "thin"? And how much, if any, does that actually contribute to longer lasting engines? And last but not least you have oil in crankcases longer than ever before. 10,000 miles is normal today. A lot of arguable variables going on. And it's likely there will never be a simple, valid answer one way or the other.

 

[dlundblad]

Originally Posted By: nap
Originally Posted By: Donald
Before you can run thicker oil than is listed in the owner's manual, one should be required to submit evidence in the form of plastigauge measurement of bearing clearance from all main bearings.


Before continuing the "thick oils won't fit through the tight clearances of modern engines" argument, one should submit plastigauge measurements showing what these clearances actually are.

Skip both and see what is recommended by the manufacturer in Europe and/ or Australia.

 

[javacontour]

Some of the SVT offerings from Ford and the M offerings from BMW require oils thicker than your traditional 5W30 or thinner offerings today.

I recall back in the early 2000s where some super high performance Mustang required a 20W50 or similar. Basically a street legal race car.

I doubt there are too many run of the mill rides that require anything thicker than a 5W30 in North America.

 

[UncleDave]

OP

Engine clearances are not a static number over time.

Lightly loaded brand new vehicles can run water thin oil and be just fine for a long time - but ultimately time takes its toll.
Especially in a hard working truck.

Have you ever owned a car or more specifically a truck with an oil pressure gauge for 1-2-300K miles?

As the vehicle ages and clearances open up, or after a long climb up a steep hill towing a heavy load oil pressure with the factory recommended grades show low or almost no oil pressure at idle after a stretch of hard work and lots of miles on them.

I've had trucks so worn out that after a hard climb if they go back down to idle in gear with the AC on the pressure gauge will show almost no pressure - sometimes enough to get a warning light.

Stepping up a grade often results in getting back some oil pressure all the way around and allows the older vehicles some more run time before a rebuild is necessary - but then again on bitog nothing wears out (lol) so there is never a reason to go up a grade from the original factory recommendation and no one rebuilds anything..

UD

 

[ammolab]

Originally Posted By: javacontour
Some of the SVT offerings from Ford and the M offerings from BMW require oils thicker than your traditional 5W30 or thinner offerings today.

I recall back in the early 2000s where some super high performance Mustang required a 20W50 or similar. Basically a street legal race car.

I doubt there are too many run of the mill rides that require anything thicker than a 5W30 in North America.


Yes, S54 powered 3.2L 6cyl BMWs (M3 & M Coupe) as well as some of the V8 M5s required 10W-60 oil.

 

[RooflessVW]

Originally Posted By: Donald
Before you can run thicker oil than is listed in the owner's manual, one should be required to submit evidence in the form of plastigauge measurement of bearing clearance from all main bearings.

Will the oil get stuck?

 

[69Torino]

Originally Posted By: tomcat27
The bearing clearances on my SBF are .0035, so I suppose I need to run a thicker oil. I'm using 20w50


Exactly what I would do on that blueprint. Or 15w-50 synth. (Basically the same thing) Point is I would be in a 50 weight at .0035

 

[nap]

Originally Posted By: dlundblad
Skip both and see what is recommended by the manufacturer in Europe and/ or Australia.


Sometimes the engines might indeed be different. One example that I know of is Honda Accord 4cyl 2006-2007:

Eur / Jp / Aussie / NZ market got the K24A3 engine with 10.5:1 compression ratio.

US / Can got the K24A8 engine with 9.7:1 compression ratio (probably due to the [censored] gas here).

 

[Snagglefoot]

Originally Posted By: 69Torino
Originally Posted By: tomcat27
The bearing clearances on my SBF are .0035, so I suppose I need to run a thicker oil. I'm using 20w50


Exactly what I would do on that blueprint. Or 15w-50 synth. (Basically the same thing) Point is I would be in a 50 weight at .0035


Party on!

 

[Dave1027]

I'm thinking it's because today's oils are so much better, that enables the use of thinner oils without risk to engine longevity. I've seen a lot of excellent 0w20 UOAs on this forum that essentially proves it in my mind.

 

[Trav]

Originally Posted By: Donald
Before you can run thicker oil than is listed in the owner's manual, one should be required to submit evidence in the form of plastigauge measurement of bearing clearance from all main bearings.


Plastigage is not the best thing for measuring bearing clearances accurately. Read the comments under the pictures.

https://www.hotrod.com/articles/plastigage-vs-micrometer/

 

[supton]

Didn't I read here that the older SBF's had a weak oil pump drive which could shear if very thick oil was used?

I've always been amazed that the GMC V6 big block had SAE20 allowed, and that was back in the 60's for a truck engine.

 

[Graham Piccinini]

Originally Posted By: camrydriver111


Are there engines that don't do so well if you use an oil too thin or too thick? Or can you just run whatever you want?



Case #1 - 2009 Toyota Tacoma with 55k miles on 2.7L 4 cylinder. It is short tripped, only put 25k miles on it in the last 6 years of ownership. Due to short trips the oil never gets up to temp, except for occasional highway drives. 0w40 in that engine always felt sluggish due to never getting up to proper operating temp. 0w20 on the other hand feels right at home. Circulates quicker, and doesn't crush the oil filter media anymore, as 0w40 did with 1yr OCI.

Case #2 - 1999 Lexus GS400 with 212k miles. With 5w30 synthetic oil it would smoke every startup. Not "seafoam" levels of smoke, but close. With Mobil1 10w40 HM no smoke and smoother operation overall.

In conclusion - use the type and grade of oil that your engine has the best feedback with, but always consider your climate. No 20w50 in Alaska (unless got a webasto block heater or similar), and no 0w20 in Sahara.

 

[ka9mnx]

Originally Posted By: supton
Didn't I read here that the older SBF's had a weak oil pump drive which could shear if very thick oil was used?

I've always been amazed that the GMC V6 big block had SAE20 allowed, and that was back in the 60's for a truck engine.


Yes on both accounts. If the oil was too thick and it was too cold, bam.

Surprisingly, GM allowed 20w in most of their vehicles in the 60's. But in that beast of a V6? I worked on many and they were a POS gas guzzler. They even made a V8 version (very rare) that would make the exhaust manifolds glow red.

 

[Malo83]

20w50 in my tired 35 yr old 305 with 230K on the clock, doesn't leak as much oil as with a 10w30

 

[FCD]

My Capri specs 20w-50 from new, the British Ford Essex V6 has unusually big clearances and large oil galleries.
It loves Valvoline Vr1 and its 5.0 HTHS but does fine on the cheaper Shell Helix i put in it sometimes.

 

[CT8]

what gives you that idea?

 

[CT8]

Originally Posted By: Vladiator
Originally Posted By: camrydriver111


Are there engines that don't do so well if you use an oil too thin or too thick? Or can you just run whatever you want?



Case #1 - 2009 Toyota Tacoma with 55k miles on 2.7L 4 cylinder. It is short tripped, only put 25k miles on it in the last 6 years of ownership. Due to short trips the oil never gets up to temp, except for occasional highway drives. 0w40 in that engine always felt sluggish due to never getting up to proper operating temp. 0w20 on the other hand feels right at home. Circulates quicker, and doesn't crush the oil filter media anymore, as 0w40 did with 1yr OCI.

Case #2 - 1999 Lexus GS400 with 212k miles. With 5w30 synthetic oil it would smoke every startup. Not "seafoam" levels of smoke, but close. With Mobil1 10w40 HM no smoke and smoother operation overall.

In conclusion - use the type and grade of oil that your engine has the best feedback with, but always consider your climate. No 20w50 in Alaska (unless got a webasto block heater or similar), and no 0w20 in Sahara.
This pretty much explains it.