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What I get out of it is that 5W used to be considered too light weight to protect cold starts above 60F. And SAE 20 used to be considered too thin to protect above 80F.
Damn...even I know that chart is based on lubrication and engine technologies from the past century.
That chart was used back when API grades were sufficient to determine if the oil was adequate for a particular engine.
Damn...even I know that chart is based on lubrication and engine technologies from the past century.
That chart was used back when API grades were sufficient to determine if the oil was adequate for a particular engine.
There are a few problems with saying the chart is too old. One, Amsoil and many others still have similar charts to autozone's chart on their websites with similar recomendations. Two, common use of synthetics is almost a century old. Three, it's not like they say oil doesn't work above X temperature, they say use a higher weight, so if one weight works and another doesn't it can't be because of thermal breakdown. Four, most if not all modern manufactures recommend higher weights for higher performance applications due to temperature concerns when not cruising for pure mileage. Jag is the only one I've found that doesn't.
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I believe you.
If thin oil protected as well its what we would use all the time, not just at cold start. the reason we dont want thin oil at operating temp is the reason you cite.
OEMs are fighting to keep startup emissions down (when they are atrocious) thin oil helps get cams and such online faster.
The cool thing about science is that your belief in it is irrelevant. An engine will have an oil viscosity that is optimum. Multigrade oils better maintain a uniform viscosity over a temperature range. If grade 30 is ideal at operating temperature, 0W is closer to that at room temperature than 5W. Chapter 2 here explains that:
The cool thing about science is that your belief in it is irrelevant. An engine will have an oil viscosity that is optimum. Multigrade oils better maintain a uniform viscosity over a temperature range. If grade 30 is ideal at operating temperature, 0W is closer to that at room temperature than 5W. Chapter 2 here explains that:
Scientific "optimum" means verified and validated back to requirements. That is the heart of the question, when Jag says "optimum" do they mean "optimum" for CAFE requirments or for customer requirements?
Since 16 and 20 weight oils basically didn't exist in the automotive word before the CAFE squeeze, it seems these ultra thin oils are to provide "adequate" protection while avoiding fines. The funny thing is these thin oils only increase mileage by 1.5%-ish according to the many online charts.
Question - Are we wearing out our high performance engines significantly faster for 1.5% more mpg? How convenient is that for manufacturers who can claim the devil made them do it.
I noted that for optimum mileage, our V8s in 8th at 55 mph spin at 1100 RPM. AKA, idle.
Are we we really optimizing oiling protection for idle?
Scientific "optimum" means verified and validated back to requirements. That is the heart of the question, when Jag says "optimum" do they mean "optimum" for CAFE requirments or for customer requirements?
In the case of comparing 0W-30 and 5W-30, when the oil is at operating temperature, the two oils are rated identically.
Originally Posted by RacerX
I noted that for optimum mileage, our V8s in 8th at 55 mph spin at 1100 RPM. AKA, idle.
Are we we really optimizing oiling protection for idle?
If you're idling with your oil at 40C, you'd be better off with 0W-30 than 5W-30. If you're idling with your oil at 100C, either will do.
In the case of comparing 0W-30 and 5W-30, when the oil is at operating temperature, the two oils are rated identically.
If you're idling with your oil at 40C, you'd be better off with 0W-30 than 5W-30. If you're idling with your oil at 100C, either will do.
I think we all agree that the winter weight side of a variety of products is easy, as there are lots of 0W, 5W, and 10W versions of oils from SAE 16 to 60. My questions are more about SAE weight driving more normally than idling for mileage.
Assuming we use our 550 to 650 HP for a lot more than sustained near-idle cruising, is 0W-20 really a better choice for longevity than say, Amsoil 0W-40 European Performance, or Castrol Edge Supercar, or Liquid Moly 5W-40 for turbo and supercharged applications, or M1 0W-40 Eurocar?
I get that Jag has no choice but to meet CAFE standards, but does optimizing an F-Type V6 S or V8 R lubrication for near idle hyper-miling really make sense to anyone but regulators?
My spidy sense kicks in when the ECU pulls timing above 5000 RPM on the dyno.
I get that Jag has no choice but to meet CAFE standards, but does optimizing an F-Type V6 S or V8 R lubrication for near idle hyper-miling really make sense to anyone but regulators?
My spidy sense kicks in when the ECU pulls timing above 5000 RPM on the dyno.
Not sure I get the causation? Is your theory that the lower viscosity oil is not protecting at high RPM/high load, and the engine temp is rising hence the ECU pulls timing to protect engine? Seems like more testing with identical temperatures/situations would be in order before I'd go with something subject to so many variables,
Anyways, your concerns about protection/viscosity are still being debated on other forums. BMW's E90 series M3's had a low tolerance engine design and spec'd 10W-60 oil, but then the engine had rod bearing issues and failures. Some hypothesized that revving the engine over 2500 RPM when the oil was cool (and too thick) or driving too hard before the oil had gotten up to temperature were the culprit. But BMW stuck with the 10W-60 recommendation because it was felt the 60 weight oil was necessary to protect the engine in higher temps. This was a car sold between 2008-2013, so not exactly ancient history.
I think if I was going to change oil grades from the manufacturer's spec, I'd try a modest bump from 5w-20 to maybe 5w-30 max. Just my 2 cents...
Not sure I get the causation? Is your theory that the lower viscosity oil is not protecting at high RPM/high load, and the engine temp is rising hence the ECU pulls timing to protect engine? Seems like more testing with identical temperatures/situations would be in order before I'd go with something subject to so many variables,
Anyways, your concerns about protection/viscosity are still being debated on other forums. BMW's E90 series M3's had a low tolerance engine design and spec'd 10W-60 oil, but then the engine had rod bearing issues and failures. Some hypothesized that revving the engine over 2500 RPM when the oil was cool (and too thick) or driving too hard before the oil had gotten up to temperature were the culprit. But BMW stuck with the 10W-60 recommendation because it was felt the 60 weight oil was necessary to protect the engine in higher temps. This was a car sold between 2008-2013, so not exactly ancient history.
I think if I was going to change oil grades from the manufacturer's spec, I'd try a modest bump from 5w-20 to maybe 5w-30 max. Just my 2 cents...
Yes, it is my hypothesis that the timing pulls on every run that day were due to engine heat. The next time had more boost but with 5W-40 Moly and had no issue with a nice straight slope into redline. It's definitely anecdotal and dynos are not well cooled in the first place, but that is also where we'd expect to see problems.
Don't get me started on BMW engine disintegration, it happens early and often on motors with perfect maintenance records. And shouldn' t a 0W to 10W have less than SAE 60 before warm?
You are right this debate is pretty common, but a key difference is, for example, the Porsche forums where there is driver push back against 0W-40 in favor of 20W-50 or 10W-60. IOWs 0W-20 is well beneath the baseline conversation.
Jag could help clarify by specifying if the recommended 0W-5W-20 spec is to meet carbon emissions goals or for engine longevity. It seems odd that similarly tight engines, including Ford 5.0Ls recomend SAE 30 when driven hard or SAE 50 when supercharged.
There's no doubt that CAFE tests are running our V8s near idle. There is so little heat or stress at 1100 RPM, why not run 0W-16?
Damn...even I know that chart is based on lubrication and engine technologies from the past century.
That chart was used back when API grades were sufficient to determine if the oil was adequate for a particular engine.
hi unhingd. I am considering to switch from 5w-20 to motul’s 5W30 with ester. The reason im considering that is that the median day temperature here is 44 celsius in the summer and around 22 celsius in the winter. It can shoot up to 50 celsius in the summer and i almost never seen anything below 10 celsius in the winter. Do you think this switch is a good idea?
In exceedingly hot climates, it is always worthwhile to review the use of an adequate viscosity oil and choose carefully. Although hot and sticky South Florida is not as hot as other locations, there are a great many vehicles here that benefit from a higher viscosity. A good example is the Ford 3v 5.4L V8, where the use of 10W-40 prevents cylinder head oiling problems and timing chain wear, along with cam phaser failures. In some cases, the engine won't make 100K here on 5W-20 and will easily top 330K with 10W-40.
While that's one example and it's an engine with known flaws, climate does matter.
I have a modified V6s, and I'm in the process of deciding what oil to choose. It will likely be a 5W-30. But remember, it's often 100F/38C here in the summer, and can get a bit hotter as I drive to destinations north of here.
Also of note, chains last longest with a 30 viscosity oil. Today, most engines have chains, and it has become common to replace them early. The issue is one of inadequate viscosity, coupled with long oil change intervals (combustion byproducts-soot, wear metals, evaporated fuel byproducts and non evaporated fuel) The oil change is the only way to remove such wear causing contaminates.
With that in mind and frequent failures, the better manufacturers have just now moved to coated chain pins, along with demanding improved oils that provides better protection for chains (which ain't easy to do with 0W-20 oils). Again, the fact remains, inadequate viscosity coupled with long OCI's, is often to blame.
EDIT: But the idea that oil is always getting better is no longer correct. Additives are being reduced for cat lifespan reasons. Today's oils have half or even 1/3rd the critical additives and no amount of oil base stock blending will make up for that.
Our connecting rods are configured with the cap at an angle. This is to allow a larger rod bearing and still fit the rod big end through the bore for assembly. This larger rod bearing is one trick modern engine designers are using to accommodate the low viscosity oils. As always, it's worth knowing how much force the rod bearing must withstand. When an automotive engine is making 70 or 80HP per cylinder, the loads become extreme and even the slightly larger diameter journal may be "taxed" under full power. This is where HTHS and MOFT (oil performance at elevated temperatures/oil film thickness) are of key importance.
High end road racers can use 0W-20 oil in high output engines, however to do so, they manage oil temp at about 180F. This requires significant engineering, as it is not easy to do. They also choose an oil with the highest HTHS available. Also, they don't care about wear or lifespan, really. The engine may not have to last more than about 15 to 25 hours in total.
In exceedingly hot climates, it is always worthwhile to review the use of an adequate viscosity oil and choose carefully. Although hot and sticky South Florida is not as hot as other locations, there are a great many vehicles here that benefit from a higher viscosity. A good example is the Ford 3v 5.4L V8, where the use of 10W-40 prevents cylinder head oiling problems and timing chain wear, along with cam phaser failures. In some cases, the engine won't make 100K here on 5W-20 and will easily top 330K with 10W-40.
While that's one example and it's an engine with known flaws, climate does matter.
I have a modified V6s, and I'm in the process of deciding what oil to choose. It will likely be a 5W-30. But remember, it's often 100F/38C here in the summer, and can get a bit hotter as I drive to destinations north of here.
in theory, i think it’s a great idea to do so. With those car being uk made, the weather is not as hot as neither your or my area. I actually just found out that my friend uses the 10w40 for his dual pulley F type v8 in dubai (similar weather) and ran about 70k miles with no oil loss between services. My car is an upper pulley F type R with plenty of other mods. I have had oil losses, but i think it was due to a defective pcv. I also know it wasnt due to damaged pistons since it shows no correction above 1.5 degrees at 7200rpm in my logs. I also have timed a 6.69s 100-200kmh and a low 8s 60-130mph on dragy (another clue that the engine is fine). However, on idle, i feel like the engine sounds like it has a little excessive friction. I have always been using liquimoli’s 5w20 with a ceratic additive. Will test motul’s 5w30 with ester and see how it changes.
I just change the Ravenol ECS 0w-20 every 3k miles in my garage in about 20 minutes via mighty vac. Their data with their USVO is impressive in holding viscosity....some 30's fail to hold that over time...this brand holds up for probably 7 or 9k miles, so my short OCI is just super safe. The NOACK is the best of any oil I have seen out there at this weight.
No carbon so far...JLR designed a good GDI: top tier gas, frequent oil changes, waiting for the car to warm up (super important step), and BG44k every oil change or probably more frequently....done. Racers may need more and I wonder about 0w-40....that might be the best option out there...wonder if anyone has data on that weight?
Am at 55k with the car getting fully exercised with no oil consumption at all. Nuff said. 0w-20. I changed the oil in my garage in 30F degree weather.....it was surprising how thick the 0w had gotten. I am not sure I'd want 10w in these cars at all....etc. The new oil tech is amazing....the gf-6a timing chain spec is a new thing I am looking at but I figure the frequent OCI I use is a sort of equal to GF-6a (have no idea but that is what I tell myself).
strange only that with SAE 50 (16mm2/sec) flow, and with SAE 20 only 7mm2/sec), although the 20 should actually be thinner!
this data refers to 100° C engine oil temperature!
Last edited by Andi Jaguar G; 01-30-2023 at 05:15 AM.
strange only that with SAE 50 (16mm2/sec) flow, and with SAE 20 only 7mm2/sec), although the 20 should actually be thinner!
this data refers to 100° C engine oil temperature!
I don't even know what to make of that chart. The x-axis changes units, half of which are in degrees C, and different than the 100C you mention. Can you share the source?
I don't even know what to make of that chart. The x-axis changes units, half of which are in degrees C, and different than the 100C you mention. Can you share the source?
12-20-2019, 05:42 AM
