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5w20 vs. 5w30

74K views 75 replies 30 participants last post by  amc49 
#1 ·
ford says 5w20, everyone else i've talked to (mechanics, service advisors, etc) say 5w30

as i understand the 5w20 is thinner and allows the parts to move easier (less work) thus reducing gas consumption, BUT 5w30 is bit thicker, not as fuel efficient, however prolongs the life of the engine since it lubes it better.

i just got some 5w30 (switching synthetic) 1st time i'm not using 5w20

in north america ford and honda recommend 5w20 (using 5w30 apparently can void your warranty), but ford in europe does the opposite. they use 5w30 exclusively and don't even offer 5w20.


what do you guys think?
 
#2 ·
the reason our cars take 5w20 is because our engines are desgined with closer tolerances that only the lighter weigh oil can get to. yes 5w30 sticks better but it might not get to some of the friction points as well as the 5w20 oil
 
#15 ·
That sounds correct for the majority of synthetic oils. Mercedes Benz uses an oil that (likely to be Amsoil- yay American chemical engineering) only needs changing every 25k miles or once per year. This is part of the free included service that comes with the expense of purchasing a Benz.

Most people could also change their synthetic oils at higher intervals with no reduction in engine life. Synthetic oils maintain viscosity much longer under more diverse conditions than petroleum based oils. Nearly every car owner, myself included, seems to have this vision of keeping their car until the doors fall off. When we go to the parts store, we see expensive synthetics labeled 7.5k mile service life, and figure our car will last forever if we change the oil long before the interval suggested on the label- even though we know (if we research) that this interval is suggested due to testing under extreme conditions that most cars will never endure.

Junkyards are filled with cars that were properly maintained from day one, but have died due to things completely unrelated to maintenance. Yet, every day we think it won't happen to us as we careen to work through traffic nestling hot coffee between our legs while shouldering a cell phone conversation and entering appointments on our PDA.

Maybe some people who read this have more time to do research online, and can find the results of a US military study that I read about years ago where two new trucks (likely diesel) were maintained differently: one changed oil and filter every 5k miles, the other only topped off the oil, and changed the filter. As I recall, the second truck's maintenance more cost efficient over it's life, and lasted nearly as long as the first truck- however the military still maintains vehicles based on regular oil change intervals. Not that it should surprise any American that our government is unconcerned with saving money.
 
#4 ·
I hate to drag up old stuff, but North America is the only place that I've seen where 5W-20 is called for by Ford. (Note, the SVT Zetec is supposed to use 5W-30.) Anywhere in Europe and in Australia and New Zealand they call for 5W-30 or even 10W-40. It isn't a "closer tolerance" issue, it's fleet average fuel economy regs. These "North American" engines don't have different build tolerances than those used anywhere else. What got my attention was that Nissan (I've owned one for 3 yrs.) for example, does essentially the same thing. In NA they recommend 5W-30 as the "preferred" oil, but you can use 10W-30 or 10W-40 if the temp. is over 0 deg. F. In Europe, Nissan recommends 5W-20 ONLY for temps. UNDER +14 deg. F and it is NOT recommended for "sustained high speed driving", and even the 5W-30 is only recommended for temps. below 59 deg. F. Above -4 deg. F any 10W or 15W-XX oil can be used, and above +14 deg. F any 20W-XX oil can be used. Now here's a hint........Nissan also states that...... "5W-30 oil will positively improve fuel economy". The Nissan VQ 30 engine in my car is built to the same tolerances irrespective of where it is used, so why the difference in oil recommendations? It goes back to the NA fuel economy deal again. This Nissan info came to mind when I bought my Focus and of course was confronted with Ford here recommending the 5W-20. My Nissan engine has the standard basic plain bearings, has chain (oil jet lubed) driven DOH cams with direct acting cam followers, a crankshaft driven oil pump, and a pressure regulated lubrication system just like my Duratec in the Focus, and with engineering principles being what they are, all the bearing clearance tolerances have to be within a certain range or limit to "physically work". My Nissan engine's piston clearance limit is .0004 to .0013" and I don't think you can get any tighter than that. And I'm aware of the principle of leakage, flow and cooling. Because I have a thing for (a fear of low) oil pressure, a decade or so ago I did some "real (my) world" oil testing with my '93 GM "L" body car, that had a 0 - 80 p.s.i. oil pressure gauge. Over a period of about two years and several oil changes I "experimented" with mineral oils of different oil viscosities, and one synthetic (Castrol Syntec). At that time the oil that gave me the highest oil pressure readings both at hot idle and at highway cruise was a 15W-40 (Castrol RX Super). With this oil the oil pressure was about 60 - 65 psi at highway rpm and it never went below 30 psi at idle. This oil of course "starts life" as a SAE 15 oil, so no surprise there. This had been my regular oil that I had used in this GM car and a VW Rabbit for a number of years. It of course does not meet the present API specs. I tried the Castrol Syntec 20W-50 and much to my surprise it had almost the identical results as the RX Super. I tried a 10W-30 (Castrol Canada XLR, now GTX) which yielded about 55 psi at cruise and about 25 psi min. at idle. 5W-30 was just starting to be recommended and available, so I gave it a shot (I think it was Castrol) and it made me nervous because at idle the oil pressure dropped to just under 20 and at cruise it barely got to 50 psi. That has always stuck with me, and I do understand that oils have improved in the last decade, and Ford has their spec. for the 5W-20, but I believe that to protect an engine under severe conditions you can't beat viscosity (actual) and the higher viscosity oils seem to have the better "high temp. shear" ratings. Also with manual tranny cars, where you invariably load the engine (pop the clutch) sometimes almost at "stall" rpm with minimum oil pressure, I want as high an idle oil pressure as possible to protect the main bearings etc. So, for me, where I live, both my cars are getting 10W-30 and because I don't feel like screwing with success, where except for my first car, every car that I've owned has never used/burned any oil to speak of and I've had anywhere from 110,000 to 325,000 miles on them when I got rid of them, and I refuse to use an oil that starts out as a SAE 5. BUT, with the average Focus owner ("the daily driver"), still under warranty, and because most are not going to hang onto their cars for as long as I tend to do, then using the recommended oil is probably the way to go.
 
#5 ·
I heard (on Car Talk) that the lower viscosity oil (5-20) will reach critical engine parts faster after a cold start due to it's thinness, and cold starts create over 90% of an engine's wear. That's why I've stuck with it here where temperatures dip below 0 farenheit a few times per year.
 
#7 ·
> it's fleet average fuel economy regs. These "North American" engines don't have different build tolerances than those used anywhere else.

Bingo.

The lower viscosity is only to help their EPA Fuel Economy numbers.

But yes, 5W-20 might be a better choice for the Winter months, particularly if temperatures get below zero F on occassion.
 
#8 ·
i have 5w20 AMSoil... and i have a 0 - 100PSI electric oil pressure gauge... at idle its i say around 15psi... and crusin it goes around 64psi... but when shifting at high RPM's i want to say it peaks around 90-95psi....

should i go to 5w30? i live in FL, coldest it gets where im at is like low 30's only for like a night or 2... then after our coldest night it only gets down in the 40's/50's... and when its that cold and im gonna drive i let my car warm up to atleast 125F before i move.
 
#10 · (Edited)
im using 10w-30 right now.. only cuz my car sat since aug 28th (car accident wreck my sisters zx2 messed my legs up pretty good) i am goin to be doin a flush with 5w-20 as well as doin a tranny flush and brake line flush.. im goin to be using royal purple.. dunno if royal purple makes brake line fluid tho..
o and im pretty sure my oil cap says 5w-30
 
#11 ·
I find it hard to belive that you realy NEED to warm up your car in FL... I'm sure it doesn't hurt anything but maybee only at hte lowest lows, like at 30.
 
#22 ·
i heard this from my delivery advisor at work that the motocraft was cut open and compared to other filters and was one of THE best filters... im starting to wonder how it compares to the K&N filter that i have on my engine now....


and i let my car warm up for a min or 2 not to full warm up... and usually thats in the morning when its alittle cool out.
 
#13 ·
Why in the world would anyone be concerned about maintaining high oil pressure? It is the exact opposite of what you want. Low pressure (assuming your pump is good) indicates your getting oil into the engine vs. a plug or obstruction. The only good reason to watch your oil pressure is for a sudden change, which would signal a possible problem.
 
#14 ·
Remember that there are areas of North America in winter where cars of all kinds are being operated normally in temps. down around -30 or colder. At those temps 5W anything is going to have an actual viscosity heavier than any heavier (10W-xx for example) recommended oils in more "southern" areas, where the temps are above freezing or higher. The "northern" cars survive just fine. How low do you want to go, S0COFused? In some UNREGULATED oil pressure systems in engines where obstuctions in oil supply lines and oil jets may occur and starve a bearing for example, high oil pressure is a concern. Some diesel engine and some gas turbine manufacturers that are prone to oil coking and carbon deposits get concerned with a sudden increase in oil pressure, because an obstruction causes a sudden drop in flow (the output), BUT that is not going to be an issue in your car. Low oil pressure in your car IS usually caused by a high flow, but it's a flow so high that the pump can't keep up. This high flow is caused by low actual oil viscosity because of the oil viscosity rating, high oil temp, excessive leakage out of the bearings associated with the actual low viscosity of the oil and oil leakage from the bearings because of excessive clearances from the assembly procedures, or from wear. You DO NOT want low oil pressure in your car engine!
 
#16 ·
how many quarts does our Focus take guys? The manual says 4.5 but I dont like the fact that its not an even amount. So 4 or 5 ok?

Btw, Consumer Reports magazine does not recommend syntethic oil. Its article went into further depth on why regular oil is better than synthetic.
 
#17 ·
Disagree Grumpy.
The "northern" cars survive just fine. Well maybe NOW they do! :) In N.D. way back, I still recall the tap,tap,tap and having to let the car warm before moving it (if they would move. sometimes not). A lower Vis oil would have been good.
If your engine is in good repair, then the pump is going to keep up even with a lower Vis like 5w-20 if it was designed for it. And I don't mean ultra low pressure, rather, if you normally have 25psi of pressure at idle, and it changes drastically in a relative short time period, then you know something has occured and can take measures before it gets expensive (That's a pet peeve of mine with the oil lamp, only alerts on low pressure). My point I guess then is, know your normal pressures for your area. And as long as they remain normal your good. I would also not be to keen to take a recommendation from a shop or dealer. If they can get a 50% markup for 10w-30 vs 20% for 5w20, Well, it's not rocket science which one gets the recomendation.
Diesel and Gas Turbine are beyond the scope of this forum yes?
whynotthinkwhynot >> I can personally attest to something like this. In the service we had a truck (Duh!) that had 200k+ miles on it and the original filter. They would just top the oil every so often (Dodge crew cab). That thing fired up every time even in cold (-20's or so). We all wished it would die as the interior was really bad! ;-D It was still in use when I got out.
 
#19 ·
up here temperatures range anywhere from -40F in winter to 95+ in summer... i've always used 5w20 so far (changed by the dealership) i've never had any probs with the 5w20 in the last 3 years..
recently i switched to 5w30... i read a whole bunch of articles and i think the 5w30 will do better...

i've also heard of people changing their oil according to the temperatures outside..... 5w20 for the winter and then switching to 10w30 and heavier in summer.
that might also be an option-?
 
#21 ·
What the heck do you think is going to cause a blockage and where anyway? Oil is going to a lot of places most of which have tight clearances and relatively low flow, so unless you had a blockage of a main gallery which is unlikely, you would never see any oil pressure changes due to the blockage, but my guess is you might hear or feel something. As you stated the oil pressure is affected by a lot of variables, and the oil pressure goes anywhere from a high max. pressure when cold especially, to a low hot idle oil pressure. I'll bet your "tapping" was a common hydraulic lifter issue and a lower viscosity oil MAY have "helped", but that's apples and oranges with our engines. In my opinion "cold start wear" is overstated. First, there is oil still on the oil wetted parts of the engine. It hasn't just disappeared or drained from the bearings etc. Oil does "cling" to these parts after shutdown so there is a film of oil protecting these parts. Unless you are a clutz and load the engine the instant the first cylinder fires, then "normally" as the engine oil system takes the fraction of a second (depending on the actual oil viscosity) to build some pressure, nothing is wearing here in reality. There is as yet also no heat to speak of and the engine is only turning itself over. It's funny too, because our engines build up oil pressure quickly because the pump is driven by crankshaft.....old tech. pushrod engines for example, usually had the oil pump driven directly by the camshaft/distributer shaft rotating at 1/2 crankshaft speed of course. I am far more concerned with wear that can occur under high load, high temp. conditions. The start and the warmup don't concern me.
 
#25 ·
> because a seller can get 10w-30 cheaper than a 5w-20, but still sell it at the same price or close to it.

In actual fact, at least around here, 5W-20 would provide more profit than 10W-30. They both are marked up the same percentage, but the 5w-20 is more expensive, so the same percentage markup results in a higher profit in total dollars.

If you check the public corrospondence between the EPA and Ford regarding the use of 5W-20 in the MPG tests, it is obvious that Ford is specifying 5W-20 in the US purely for EPA MPG reasons.
 
#26 ·
Logic Error. (contradicting statements)
They both are marked up the same percentage >><<5W-20 would provide more profit than 10W-30 >><<5w-20 is more expensive >><<the same percentage markup results in a higher profit in total dollars.

Let me put it another way. A buyer enters my store. The buyer compares the price of 5w-20 oil (which is expensive) to more commonly available 10w-30. So they buy the more reasonably priced 10w-30. But what the buyer does not realize is that I am making an extra nickel profit per quart on the 10w30 because I can get a greater bulk discount from my supplier. So if you (as the buyer) were to ask me about oil, which one would you think I (as the seller) would recommend? It is called 'laze fare' and it is very much alive in the U.S.A.

"Ford is specifying 5W-20 in the US purely for EPA MPG reasons" >> Probably, it would take less H.P. to pump a thinner oil so that makes sense. But remember that to do that they had to engineer the system to run well with that thinner oil. If you go with too heavy oil, you will get great oil pressure and poor lubrication.
 
#27 ·
Logic Error. (contradicting statements)
They both are marked up the same percentage >><<5W-20 would provide more profit than 10W-30 >><<5w-20 is more expensive >><<the same percentage markup results in a higher profit in total dollars.
===================================

No logic error at all.

Say the mark up is 20%. 5W-20 cost the store $2.00 a quart, while 10W-30 costs the store $1.50 a quart. With a 20% mark-up, the 5W-20 sells for $2.40 a quart, or a 40 cent profit to the store, while the 10W-30 sells for $1.80, or 30 cents profit to the store.
 
#29 ·
> Ah! OK. Now I see it.

Yes, Walmart and most of the auto store I patronize sell 5w-20 at a higher price than 5w-30, and I doubt that they are eating the extra cost and not using the same percentage markup, e.g., the Mobil 1 5W-20 is typically priced noticably higher the Mobil 1 5W-30.
 
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