5w30 Synthetic vs 20w50 Mineral oil

tabrez.tb48de

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I would definitely use synthetic. And, when you buy oil, you buy whatever grade you want. You are not forced to buy 5w30. Find a 40 or 50 grade synthetic oil, 5w40, 10w40, 10w50, 15w50, or 20w50... and keep driving. Shops/mechanics don't tell me what to buy and I don't care about their recommendations. I tell them what I want and that's it. You might not find every grade with every brand. So, shop other brands too.

I haven't seen automotive synthetic Castrol 50 grades in stock anywhere. I can usually order the 10w60, 10w40, and their 5w40's. Their website shows Castrol syntec 5w-50. So, you'll have to check to see what is available in your local store.

Amsoil does have Premium Protection 20w50 and Signature 5w50. These two would be easy choices.

Since you want to increase your oil change interval from 5k to 10k km, I would make sure that you check the oil level often and top it off frequently.
Yeah, even i was thinking on that to go for the 20w50 amosil. but somewhere i read that Higher Viscosity Index for Synthetics is not good always, means it would be thicker compared to a mineral oil 20w50 Film thickness. If that is the case, wouldnt my mileage drop further?
Again, i am new to these things and not sure what does a VI mean.
 

tabrez.tb48de

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In the USA, the same vehicle would spec 5w-30.

For the additional heat in the UAE, I would run a 5w-40 Euro. I'm not a big supporter of running diesel oil in gasoline engines.
Yes, thats what even the websites show me. But it would have been better if it was running on 5w30 from the beginning which currently isnt the case here.
 

tabrez.tb48de

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What brands and viscosities do you have available in the UAE?
Here in the UAE,
20w50 Mineral oil - readily available of all brands (Amsoil is also available)
10w40 Semi-Synth - readily available of nearly all brands (Amsoil doubtful)
5w30 Synth & Semi-Synth - Easily available (of all brands)
5w40 Synth - Becoming rare and hard to find these days
5w50 Synth - Very rare and expensive
10w60 Synth - Very rare and expensive
0w20 Synth & Semi-Synth - Market is flooding with these
 
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Yeah, even i was thinking on that to go for the 20w50 amosil. but somewhere i read that Higher Viscosity Index for Synthetics is not good always, means it would be thicker compared to a mineral oil 20w50 Film thickness. If that is the case, wouldnt my mileage drop further?
Again, i am new to these things and not sure what does a VI mean.
Well, you read wrong. Use any synthetic 50 grade available to you and keep driving.
 
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The way I see it is... you have a minimum oil film thickness required to minimize wear, and anything more is just robbing energy with no benefit. Yeah, you could say having some headroom for MOFT is a good idea. I don't care for it as to me "headroom" means "tolerance," and I don't like tolerances. You want headroom? Use a better oil. That's my thoughts on it. No issue with having viscosity headroom though, just not something I personally care about.

I stand by my thoughts that the only engines that actually need a 50 grade oil are 3000+ hp Pro Mods. The ambient temps are <10°C higher than what it gets here in South Carolina on some hot days in the summer. In my vehicles, the only difference between 20°F and 100°F is the time it takes the oil to get to operating temp. Once warmed up, it stays in the same range within ~10°F. There's a bigger difference in oil temp between towing and not towing than there is with an 80°F swing in ambient temp.

In fact, the only time I've seen a >10°F difference in operating temp was when I used a higher viscosity oil. Let's say the 20W-50 robs just 1 hp over the 5W-30 while cruising due to hydrodynamic friction. 1 hp is 745.7 watts. Using the specific heat capacity for mineral oil (~1,880 J/Kg-J) and a sump capacity of 6 quarts, we get a temp rise delta of 8.7°F every minute. If you cruise for 10 minutes like this, that's an extra 87°F of heat generated in the oil. Much of that can be dissipated but not all of it. The oil will run hotter.

If the 20W-50 was a group IV/V blend, which has a higher heat capacity of ~2,150 J/Kg-J, the temp rise delta would be 7.6°F per minute.

Given sufficient MOFT with either one, if forced to choose between a 5W-30 at 230°F operating temp vs a 20W-50 at 250°F, I'm choosing the 5W-30.
 
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Too bad we all don't know what sufficient MOFT is for every engine, and the operating temps of every driver style in the world.

So, if the threadstarter wants a 50, then so be it. But, the threadstarter seems to be fed some misinformation and can use whatever he wants. Engine already had a full life on 20w50. Its working. Didn't mention needed a rebuild or burning a quart every 500 miles like so many complain on various forums.
 

ZeeOSix

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The way I see it is... you have a minimum oil film thickness required to minimize wear, and anything more is just robbing energy with no benefit. Yeah, you could say having some headroom for MOFT is a good idea. I don't care for it as to me "headroom" means "tolerance," and I don't like tolerances. You want headroom? Use a better oil. That's my thoughts on it. No issue with having viscosity headroom though, just not something I personally care about.
How do you know the MOFT is always thick enough in all driving conditions over an OCI to prevent added wear compared to a thicker oil like with a grade higher? Nobody can zoom inside of journal bearings to take a look without tearing an engine apart under controlled testing procedures. Going from a xW-20 to a xW-30 isn't going to cause the fuel mileage to change enough to see unless you were measuring it in a very controlled lab test. But going a grade up in viscosity like that will increase the MOFT headroom. I'd rather have a little more shear drag than possibly running on the ragged edge of zero MOFT. I drive my stuff hard once and awhile, and I want the added protection headroom when I do get on it.

You don't get more MOFT headroom from using a better oil ... whatever "better oil" actually means. Nothing takes the place of viscosity when it comes to creating a protective oil film between moving parts - laws of Tribology don't change. And in terms of better film strength (if that's what you mean by "better oil"), there's no way to really rate that accurately, like 540 Rat seems to try to do with the one-armed bandit.
 
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If you have access to Magnatec 10W-40, I’d use that. Seems to have a good reputation in areas it is available.
 
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The manual suggests everything from 0W-20 up to 20W-40 and
that's explicitly for temps up to 40°C/104°F.
Honestly, I don't see any reason to go beyond that (and run 50).
So again, I repeatedly vote for a decent 5W-40 and I think it's a
great idea to find a synthetic with Porsche A40 and/or MB 229.5
approval.
Let's not forget the OP mentioned he's seeking for fuel efficiency.
.
 

FCD

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The manual suggests everything from 0W-20 up to 20W-40 and
that's explicitly for temps up to 40°C/104°F.
Honestly, I don't see any reason to go beyond that (and run 50).
So again, I repeatedly vote for a decent 5W-40 and I think it's a
great idea to find a synthetic with Porsche A40 and/or MB 229.5
approval.
Let's not forget the OP mentioned he's seeking for fuel efficiency.
.
He also said synthetic 5w40s are hard to find and expensive over there, while syn-blend 10w40 is easy to find.
I don't know of any A40 approved 10w40s but there are some with MB 229.3.
 

Jackson_Slugger

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It’s now called GTX Full Synthetic. No more Magnatec.
In the US people tend to forget that that was actually Castrol's 2nd try at marketing the "Magnetec" line in NA, they did it way back in the 90's-to-early-2000's. But it definitely exists in other markets and always has...
 

Jackson_Slugger

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He also said synthetic 5w40s are hard to find and expensive over there, while syn-blend 10w40 is easy to find.
I don't know of any A40 approved 10w40s but there are some with MB 229.3.
Well, if a Suzuki (GM) 2.4L needs anything, it's the A40 spec!

But 5W-40 would be ideal, but 10W-40 is fine here and there won't be a huge difference in fuel economy, though who knows if it gets cold in the winter months there as some deserts get quite cold...

Apparently in January it gets down to about 57F :D
 
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Complete with concerns about “clearances” and “protection”. At least it wasn’t tolerances.

In that climate a 50-grade oil with a 20W winter rating is just fine.

Except it might not actually have a much higher viscosity under shear than a good synthetic 5W-30. A mineral base oil will have a viscosity index between 80 and 100 and is propped up to 130 ish by VI. given the oil will run hot there I doubt it's actually any more viscous for lubricating, though there will be less side leakage out of bearing, which might not be a good thing either.
 
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