OHC engines and oil viscosity

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In another thread, it was written, "For any kind of OHC engine, I think it's important to get the oil flowing to the top end of the motor ASAP, even in warm weather. So I recommend 5w-20,0w-30 or 5w-30 grades for these instead of a 10w-30 to minimize camshaft & lifter wear while the engine is warming up. For a pushrod type engine this probably isn't as critical...." European engines have had overhead cams, high viscosity oil, and very long engine life for many years. My U. S. market Volvo with dual overhead cams calls for 10W-30 between 0°F and 100°F, and 15W-40 above 70°F. My Toyota DOHC engine allows for 10W-30 above 0°F. Anybody know why the idea of lighter vis oil for OHC engines is going around?...Maybe due to design problems in some of the early U. S. OHC engines? Ken [ April 22, 2003, 01:32 PM: Message edited by: Ken2 ]
 
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Ken, I can remember reading about some top end oiling issues with some of these domestic DOHC, V-6 and V-8 engines in cold climates. The Euro motors you are talking about are probably straight fours or inline sixes that have been speced to run heavier grades. So the oil pump, oil galleries, bearing clearances and drainback ports have been sized accordingly. My five cylinder, 2.3L, 1990 Audi recommends 20w-50 down to 14F/-10C and 15w-40/15w-50 down to 5F/-15C. Those just happen to be the old SAE J300 standard test temps for 15wt and 20wt grades, for CCS viscosity. I like the German/Swedish engineers - at least they seem to give some thought to these things ....
 
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Ken2, The other thing I wanted to add is that if you compare the relative viscosities of even a 0w-30 PAO based synthetic @ 40C and 100C, it's about five times as thick @ 40C. A 10w-30 is about six times as thick at 40C as it is @ 100C. So I don't think you are getting very good oil circulation to the top end of the motor when the engine is first started and while it's warming up, even in fairly mild weather. I guess this would fall under what I'd call "best practices" for lubrication. I think it makes a lot of sense if you look at trying to pump oil to the cam bearings, lobes and lifter bodies, during the startup/warmup phase of operation. On a similiar note, an SAE 5w-20 @ 40C will be about 20% thinner than a 5w-30 @ 40C. So it even makes sense that 5w-20 grades would provide a benefit in terms of reducing valvetrain wear in colder climates. I believe Ford considered this with regards to the OHC, "Triton" V-8s and 6.8L V-10 before deciding to go to 5w-20. It's certainly something I would have had in any trade study of this issue. TS
 
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These are also engines with timing belts instead of chains. The Ford 4.6L SOHC and DOHC use chains, and the tensioners use oil pressure to pump themselves up. Not to mention to get from the pan to the heads in the DOHC motor, the oil has to travel four feet.
 
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Generally thicker Euro-spec oils have higher levels of ZDDP, hence less valve train wear with OHC engines. My BMW also has a zero-drainback oil filter mounted up high which may help. American auto manufacturers and the API are fixated on CAFE. This "quick oil flow at startup" thing is starting to sound like a way to rationalize thin oils to the public. This could be of value in the winter in the upper midwest and Canada, but not for the rest of us.
 
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quote:
Originally posted by Jimbo: Generally thicker Euro-spec oils have higher levels of ZDDP, hence less valve train wear with OHC engines. My BMW also has a zero-drainback oil filter mounted up high which may help. American auto manufacturers and the API are fixated on CAFE. This "quick oil flow at startup" thing is starting to sound like a way to rationalize thin oils to the public. This could be of value in the winter in the upper midwest and Canada, but not for the rest of us.
EXACTLY! Fred... [Smile]
 
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So basically Ford/Honda are using these oils for the reasons above and not fuel efficiency? I'm not sure if I buy it. Does this also just apply to OHC engines? [ April 22, 2003, 07:59 PM: Message edited by: buster ]
 
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I am on my sixth VW. These are very tough 4 cylinder over head cam motors. The cams rub directly on bucket style lifters. I live in an area where the winter temp goes down to aprox freezing and summers are in the 80degs. After 200,000 miles there is no cam wear and the cross hatch is still clearly visable on the bore up to about 100,000 miles. These six VW's are all in the same family and get similar service. Most of them have had Quaker State 20W - 50 as this was the recomended oil a few years ago. Most euro manufacturers allowed a range but sugesrted you stick to the thick side. I still have the shop manual for my 1975 Rabit and the clearances are about the same when compared to my new 2003. I just don't think I ever will be able to use a *W-20 oil. Old school I am afraid......
 
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I don't think anyone at this point really knows what the deal is with 20wts. So far we have: CAFE, Better Flow, and now OHC. How about we try UOA. [Big Grin] Once this Mobil 1 0w-20 comes around, we'll start to see more 20wt. UOA.
 
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its for CAFE. Otherwise explain how a 2000 4.6 uses 5W-30 while a 2001 4.6 uses 5W-20. Same engine, same components, there haven't been any major modifications that would require a thinner 5W-20. So that rules out cold flow and better protection for OHC (considering from 91-00 all OHC FOrd mod motors used 5W-30). That leaves fuel efficiency/CAFE which is what the reason is - this comes from several inside sources at Ford.
 
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Metroplex, I find it curious that you have so much to say about the evils inherent in 5w-20 oils, yet you haven't presented any data that shows their use results in significantly higher wear rates in the Ford/Honda engines that call for them. I challenge you to run a controlled test in your Ford, with both 5w-20 and 5w-30 grades. See if you can show that the use of the 5w-20 results in a statistically significant increase in wear rates - even in hot weather. I'm willing to bet right now that the wear rates will be so close you won't be able to tell one from another. All the 5w-20 oils that meet the newest Ford spec have to pass a double length Sequence IIIF test, so they are actually formulated to a higher quality level than a 5w-30 oil that only has to run for 80 hours. That's why so many of them are using at least some Group III basestock. Most of the 5w-20 oils I've seen are formulated right at the upper limit of the SAE 20wt range. Most of the 5w-30 oils are formulated at the very bottom of the SAE 30wt range to optimize fuel efficiency. In terms of high temp/high shear viscosity, which is the most relevant parameter to consider, the 5w-20 and 5w-30 oils I've seen are within about 3%-5% of one another. The SAE papers I've read on studies involving 0w-20 and 5w-20 oils show that they test out about the same as 5w-30 grades in terms of wear protection, while providing a fuel efficiency advantage of 1%-2%. It really isn't that big a deal .... Ted
 
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Ted, the UOA data posts on this board and recent publications has almost convinced me that the new low vis oils are "just as good" as heavier oils, at least in some applications. But I've seen no evidence anywhere that they somehow afford better protection for valve train or turbo charger parts. The TDI board was full of warnings that using anything heavier than 5W oil was going to ruin turbo bearings. But have you seen any evidence for this? I suppose if some idiot were to consistently drive away from a cold start at full boost there could be accelerated wear, but not with normal driving at temperatures at least 20 degrees above the pumpability limit of the oil. Oil pumps are positive displacement devices, so the difference in the time for the lube to reach the valve train and turbo bearing for a 5W vs a 15W oil is only significant at very low temperatures.
 
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I can't honestly say I've seen any significant difference between 5w-30 and 10w-30, and big diesel engines still run 15w-40 in some pretty cold temps. Since you've run the Amsoil 15w-40 and Delvac 1, 5w-40 in some pretty cold weather, maybe you can tell me? FWIW, I always thought the whole TDI crowd was a bit obsessive about the whole viscosity issue. Anything from a 0w-30 to a 15w-40 seems to work just fine in that application; provided it's CH-4 or CI-4 rated. I've been recommending the Series 3000, 5w-30 to get a little better performance and fuel efficiency out of that little motor, but I'd have no issues running the Amsoil 15w-40 in my own TDI. Give me some time on the issue of valvetrain wear ...perhaps when my little 0w-20 experiment is over I'll have some data that will hold up to peer review - if I still have an engine left [Wink] I did actually get a lower rate of iron wear on the most recent analysis with 5w-20, even though my truck sat outside this winter for the first time. My wifes Audi TT quattro roadster now gets the other spot in the garage [Frown] Ted
 
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TooSlick: ask yourself this: Why is Ford's 5W-20 a Synth "Blend" and not a dino? Of course the meager UOAs done by wimpy drivers (3k miles highway driving on a new car or something ridiculous like that - at least wait 10k to 15k miles for the engine to wear in before sending in for a UOA come on what a fuggin waste of $20 on an analysis) show that the synthetic 5W-20 outperforms the dino 5W-30. Big surprise. You're comparing apples to oranges. If you read up on what I've written about 5W-20 in the past I was about to try it out but seeing how weak some of these pro-5W20 arguments are I'm going to stick with dino 5W-30. Facts: 2000 Ford 4.6L SOHC V8, Romeo NPI. Uses 5W-30 2001 Ford 4.6L SOHC V8, Romeo PI, Uses 5W-20 2000 Ford 5.4L SOHC V8, Windsor PI. Uses 5W-30 2001 Ford 5.4L SOHC V8, Windsor PI. Uses 5W-20 I've checked the engine components, asked the Ford engineers, did the research and found that the 2000-2001 engines are identical in terms of clearances, parts, etc... NOTHING that warrants the NEED for a thinner oil. Do you understand so far? SAME ENGINE, NO DIFFERENCES IN CLEARANCES THAT WOULD MANDATE THE NEED FOR THINNER OIL WHEN FULLY WARMED UP Ok, next step. Why is it that Ford's own 5W-20 is a synthetic blend at the very least and NOT a Group I/II/II+ dino oil which would be less expensive for the customer? Also why is it that all 5W-20s out on the market that are non-Group IV/PAO are some form of severely hydrocracked dino oils (GRoup III)? Look at the 5W-20 prices vs 5W-30 dino. There's always about a $0.3 difference with the 5W-20 being more expensive. The answer: Ford's testing with dino 5W-20 showed that it would shear out way too quickly to a sub-20 weight oil (xW-5 or xW-10 etc). yes the weight spread isn't as great as 5W-30 or 10W-30 but look at the UOAs for dino xW-30, they almost all shear out to a 20wt or close to a 20wt after 3k - 4k miles. Patman always complains "doesn't look good, its now a 20wt..." [Smile] [Smile] [Smile] [Smile] (No offense intended towards Patman!!!) Now we move on from Fords. I was reading about how someone from Singapore? was using 15W-50 or a ridiculously high weight synthetic oil in his late model toyota Camry 2.2 In the US the Camry is using something like 5W-20 or 5W-30. Can these engines have such different clearances that would warrant the NEED to use super thin oil in the US? The major difference is that the US is subjected to the Nazi-like rule of the EPA. Ok ok the moral of the story: want to use 5W-20? Hey its fine by me, its not my car or truck. Just use a fully synthetic xW-20. Ford is crazy enough to ask me to use 5W-20 in my 2003 E-250 w/ the 5.4L SOHC V8 (260 hp and 350 ft-lb of torque). Are you willing to kill your truck towing or hauling work loads w/ 5W-20 when the E/F-series with a mod motor ran for 200k+ miles w/o any problems using 5W-30? YOU need to ask yourself some questions. 1). Why the need to use 5w-20 in the same engine that used 5w-30 a year ago? Given that there are NO significant enough changes in the engine design to warrant the need for thinner oil. Remember: 2000 5.4 Windsor PI: 5W-30 2001 5.4 Windsor PI: 5W-20 2000 4.6 Romeo NPI: 5W-30 2001 4.6 Romeo PI: 5W-20 (differences between NPI and PI include but is not limited to the heads and camshafts, which still does not justify the use of 5W-20). Keep in mind 2000 4.6 Windsor PIs in the stangs used 5w-30 w/o any problems. 2). Why is Ford's own 5W-20 a synth blend? Why isn't Ford making a dino 5W-20? 3). Would you use synth blend 5W-20 in a working truck that hauls and tows in the heat? 4). Why is Mobil recommending 0W-30 or 5W-30 Mobil 1 in engines that call for 5W-20? Yes if you ask them they'll tell you 5W-20, ask them several times presenting the evidence I wrote here (engine changes) they'll tell you to use 0W-30 or 5W-30 for more thermal stability. 5). Can you be ABSOLUTELY sure the EPA/CAFE has nothing to do with the change from 5W-30 to 5W-20??? That being said, your engines will probably last a decent amount of time assuming you're using synthetic 5W-20 which won't shear below a 20 weight at all. If you're still genuinely interested in debating this, you can also feel free to email me to discuss what I've written. [ April 24, 2003, 08:48 AM: Message edited by: metroplex ]
 

Patman

Staff member
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quote:
Originally posted by metroplex: Patman always complains "doesn't look good, its now a 20wt..." [Smile] [Smile] [Smile] [Smile] (No offense intended towards Patman!!!)
Let me explain why I say that all the time. I would say the same thing about a 40wt oil that thinned out to a 30wt, even though I know 30wt oils will protect well also. We just haven't seen any of the 5w20 UOAs on here thinning out to anything close to a 10 wt oil at all. To be a 10wt it would have to be 5.6cst at 100c or less. Not a single 5w20 UOA on here has even come anywhere near that low. They typically stay very steady in their viscosity. I'd rather run a well built 5w20 (such as Redlines!) which starts at 9.1cst and stays there, than to run a 5w30 which starts at 11.4cst and thins out to 8.8cst. When I say I'm disappointed in reports where the oil has thinned out to a 5w20, it's mainly because of the drastic change in viscosity (along with the useless sludge molecules which accompany that thinning), not because I feel 5w20 can't protect. I do feel a 5w30 that thins to a 5w20 cannot protect very well though (since with that drastic thinning also comes a degradation in the protection the oil can offer), but an oil that starts specifically as a 5w20 will be able to get the job done. 5w20 is the wave of the future, we'd better get used to it. Ten years from now I bet most automakers in North America suggest it just like most recommend 5w30 right now.
 
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You guys keep asking: "what will happen?"...I've answered that...we all keep on talking about "my car burns oil...what do I do...? Answer: "use auto-rx". Yes, newer oils are better, they can be made thinner. They work. They're blends, etc...but they WILL slowly cook over time...like a stew. Do they work? Sure! Do the UOA look good? Sure? But, long term you will get deposits gradually thickening on the inside of the engine surfaces and consumption...but, by that time the warranty will be over and it will be time for a new car. Don't know at which point in time a UOA will show this. Why doesn't someone with a toasted oil-burner post a UOA (eg. the Lumina a couple weeks back) and lets see the difference between that and a new car...what are we looking to see?
 

MolaKule

Staff member
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21,706
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Iowegia - USA
quote:
In another thread, it was written, "For any kind of OHC engine, I think it's important to get the oil flowing to the top end of the motor ASAP, even in warm weather. So I recommend 5w-20,0w-30 or 5w-30 grades for these instead of a 10w-30 to minimize camshaft & lifter wear while the engine is warming up. For a pushrod type engine this probably isn't as critical...." European engines have had overhead cams, high viscosity oil, and very long engine life for many years. My U. S. market Volvo with dual overhead cams calls for 10W-30 between 0°F and 100°F, and 15W-40 above 70°F. My Toyota DOHC engine allows for 10W-30 above 0°F. Anybody know why the idea of lighter vis oil for OHC engines is going around?...Maybe due to design problems in some of the early U. S. OHC engines?
The cam bearings need hydrodynamic lubrication from pressurized oil systems, and receives mostly boundary lubricantion when oil pressure is just starting to build up. The cam lobes and the direct-acting bucket tappets need Friction Modification and Anti-Wear additives for boundary lubrication which is supplied by the oil. Even for a pushrod-type system, the rubbing surface need to be protected by a boundary lubricant. The oil that was deposited on the lobes and buckets the night before should have sufficient FM and anti-wear additives, such as esters, ZDDP, CaCo3, boron, or Moly, to prevent dry start-ups the next day. In other words, the ideal situation is to provide a good boundary lubricant until oil pressure can provide a hydrodynamic film. And one has to realize that during cold start-up, the oil will flow ; the only problem with cold start-up is that the flow for the thicker oil is slow, but it does exist; and all this happens in about 10 or less seconds. In my view, unless we are speaking of sub-teen temperatures, the viscosity of oil that allows the oil to flow the quickest and to provide the best overall average hydrodynamic film thickness for lubrication would be the better. For most cases in North America, this would be a 10W30. Cam bearings have always needed lubricating films, whether above the cylinders or below. I looked at the design of a pushrod, low camshaft, engine (1970 straight-six) and it's cam bearings required pressurized oil as well. This engine was speced for a 10W30, BTW. I went to the library and found a book for a 1943 circa engine (straight six) in which the (low cam system) cam bearings were lubricated by a hole above the cam bearing. The cam bearing hole allowed oil that ran from above to flow into the hole and lubricate the bearing. Since the engine clearances were on the order of 0.0035" the cam journal created a large wedge of oil for lubrication. The oil from the cam bearings were simply squeezed out the ends of the bearing as new oil was sucked in. This engine was specked for an SAE 40 weight oil, BTW. I think that with advent of the new oils, this is "much ado about nothing." [ April 24, 2003, 11:14 AM: Message edited by: MolaKule ]
 
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8,937
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SC
quote:
Originally posted by metroplex: Why is it that Ford's own 5W-20 is a synthetic blend at the very least and NOT a Group I/II/II+ dino oil which would be less expensive for the customer? ... The answer: Ford's testing with dino 5W-20 showed that it would shear out way too quickly to a sub-20 weight oil (xW-5 or xW-10 etc).
You keep posting this nonsense, and each time I've called you on it. I defy you to post any objective data from Ford or Conoco to support what you're saying. The Motorcraft/Conoco 5w20 is a Group II/III blend. Ford decided to market this as a "synthetic blend," while Conoco doesn't. The ONLY reason Group III is used in the blend is because of the double-length Sequence IIIF test. A straight Group II or II+ oil couldn't pass this test because of its volatility, and it's the reason EVERY 5w20 on the market will have some Group III (or PAO) in the base oil blend. It has absolutely nothing to do with shearing.
 
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