Mechanic used 5w30..Is this a problem?

[Fizzer600]

Mechanic used Mobil 1 5w30 in my 2015 ST with 38k miles. When i asked why, he said it is due to the warmer temps we will be getting.

Is it a problem to run this instead of 5w20? Am i stuck using 5w30 going forward?

EDIT: looks like Mobil 1 5w30 doesnt meet Fords Spec but 5w20 does. Not sure how big of a deal that is...

 

[J_Bolts]

There is no issue using 5w30 in warmer temps and you are not stuck with it going forward. A lot of people who track their FiST use 5w30 exclusively and so do people with upgraded turbos. It won't cause any harm.

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[Sprinkle_Star]

I guess his concern is 5w-20, being a thinner oil, may burn off faster in hotter climates...

I remember seeing this explained in an owner's manual for another car I've owned; it said for the summer, to use 10w-30, but when cold, it mentioned using 5w-30.

However, there is no mention of this sort of option in the Fiesta manual.

I would stick with 5w-20, and I'd choose synthetic if I were you. Since there's turbocharging involved, things can get really hot which can break down conventional oil faster than synthetic.

 

[Rocketst]

It's always good to refer to the manual but if you google recommended oil it goes further than your manual does. Recommended oil is more based on the climate than this car. 5w 30 is safe. Even 10w-40 is safe during certain conditions it's normally used to track but if you drive your car hard and live in a state like Florida I can also see this being a useful weight. The first number refers to how cold you can run it while the second is how hot the weather can be before you notice it start to break down.

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[DoomsdayMelody]

There is no issue using 5w30 in warmer temps and you are not stuck with it going forward. A lot of people who track their FiST use 5w30 exclusively and so do people with upgraded turbos. It won't cause any harm.

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Honestly I’m kinda surprise track rats don’t use a thicker viscosity, I’d heard that even 15-W40 is considered the minimum thickness that you’d want.


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[SteveS]

Lighter weight oil gives less friction and greater fuel economy (and also greater power). Modern synthetics can survive the temperatures and stress better than mineral oils ever could. The old, conventional wisdom about oil weights really doesn't apply.

 

[M-Sport fan]

Lighter weight oil gives less friction and greater fuel economy (and also greater power). Modern synthetics can survive the temperatures and stress better than mineral oils ever could. The old, conventional wisdom about oil weights really doesn't apply.

Yes, this!

IF I were running open track events every single summer weekend, or just lived in a 100*F+ every single day of the late spring/summer/early fall climate, I would opt for an aftermarket, air to oil, oil cooler in lieu of super viscous oils.

(But a slightly heavier, full synthetic, 5W-30 I could definitely see. I use one myself.)

 

[Capri to ST]

Lighter weight oil gives less friction and greater fuel economy (and also greater power). Modern synthetics can survive the temperatures and stress better than mineral oils ever could. The old, conventional wisdom about oil weights really doesn't apply.

Modern engines also have much tighter internal tolerances and smaller orifices which oil must flow through than older engines. This is another reason that lighter weight oil is used. For that reason I only use 5W-20 as specified by Ford.
The OP also mentioned that Mobil 1 5W-20 meets the Ford spec, and the 5W-30 doesn't, which would make me uncomfortable. For those two reasons, if it was my car I would make the mechanic put the correct oil in. That said, if you leave it in it's probably not going to hurt anything.

 

[Ford ST]

I think some of you need to look at the oil specification for cars when they are in different countries.
I find it interesting when some cars here in America recommend 0W-20 but if the car was in Mexico it recommends 5W-30. Why do you think that is corporate average fuel economy. And please don't say heat because this also applies to Europe as well, and also many parts of America like Phoenix are just as hot as Mexico.

One thing I like about Hyundai is they don't hide this information they actually have it in the owner's manual and give you a whole list of different oil weights you can use based on your temperature range.
Yes 5W-30 is fine no problem whatsoever.

Look up CAFE and 5W-20 make your own decision after reading.


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[jmrtsus]

It's always good to refer to the manual but if you google recommended oil it goes further than your manual does. Recommended oil is more based on the climate than this car. 5w 30 is safe. Even 10w-40 is safe during certain conditions it's normally used to track but if you drive your car hard and live in a state like Florida I can also see this being a useful weight. The first number refers to how cold you can run it while the second is how hot the weather can be before you notice it start to break down.

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The first number is the viscosity at 0 degrees F, the second is at 212 F. Has nothing to do with breakdown. That is a function of the oil types and additives.

Thicker oils will work but do not meet specs here. May be better for an aftermarket turbo I don't know, but if you do that your warranty is shot anyway, LOL. A thinner oil runs cooler than a thicker one as it moves the oil faster with less resistance also reducing power loss over a thicker oil. I'm sure that is why Ford specs it for high performance/high temp engines like ours.

 

[DoomsdayMelody]

The first number is the viscosity at 0 degrees F, the second is at 212 F.

Is that backwards? I don’t know if any liquid that loses viscosity and becomes thicker as it warms up. A 5 weight oil is much thinner than a 30 weight oil.


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[HardBoiledEgg]

Yes it's a problem. Your motor is trashed now, seek Lawyer

 

[SteveS]

Is that backwards? I don’t know if any liquid that loses viscosity and becomes thicker as it warms up. A 5 weight oil is much thinner than a 30 weight oil.


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The numbers are not actual viscosity measurements; they are a grade. When you see an oil that’s rated SAE 30, this translates into an engine oil that has a viscosity between 9.3 cSt and 12.5 cSt at 212 degrees F. The other viscosity numbers have higher or lower viscosity ranges at 212 respectively. With the multigrade oils, the number with the W refers to the ability to be pumped by the engine at winter temperatures. 0W would mean that the oil can be pumped at -40F.

According to Pennzoil, "In summary, ALWAYS follow the vehicle owner’s manual to determine the correct viscosity grade, engine oil specification, and oil drain interval. However, if you live in an extremely cold climate or just want better fuel economy, you can use a “0W” viscosity grade while keeping the recommended operating temperature viscosity grade (the second number) the same (e.g. SAE 0W-20 is compatible with a SAE 5W-20)."

 

[M-Sport fan]

^^^There are also ranges within each given SAE viscosity grade, to add to the confusion, especially concerning the HTHSV measurement, but also the cSt numbers as well.

In other words, there are some 0W-20s which are as 'thick' as some lighter 5W-30s, and some 5W-30s which are as 'thick' as some lighter 0W-40s (looking specifically at you, REDLINE OILS!).

WHY I ALWAYS look at the specs, and not simply the SAE 'weight' of any oil I am considering.

 

[jmrtsus]

Is that backwards? I don’t know if any liquid that loses viscosity and becomes thicker as it warms up. A 5 weight oil is much thinner than a 30 weight oil.


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https://www.rymax-lubricants.com/updates/what-does-5w-30-actually-mean/


"In a 5W-30 for example, the number before the W describes the viscosity of the oil at low temperatures. The lower the number, the thinner the oil and the better the oil’s cold temperature/ cold start performance. The number after the W describes how thick the oil is at the engine’s normal operating temperature."

Been around a long time.....

1950s

In the late 1950s, the first multi-grade engine oils were introduced. Most of these were SAE 10W-30 multi-grades, they met the low temperature engine cranking viscosity requirements of an SAE 10W grade plus the high temperature oil circulation viscosity requirements of an SAE 30 grade.

 

[DoomsdayMelody]

https://www.rymax-lubricants.com/updates/what-does-5w-30-actually-mean/


"In a 5W-30 for example, the number before the W describes the viscosity of the oil at low temperatures. The lower the number, the thinner the oil and the better the oil’s cold temperature/ cold start performance. The number after the W describes how thick the oil is at the engine’s normal operating temperature."

Been around a long time.....

1950s

In the late 1950s, the first multi-grade engine oils were introduced. Most of these were SAE 10W-30 multi-grades, they met the low temperature engine cranking viscosity requirements of an SAE 10W grade plus the high temperature oil circulation viscosity requirements of an SAE 30 grade.

Seems like a backwards way to classify it: “here’s an oil with an undesignated viscosity but we’re telling you it acts like a 5-weight* when cold and a 30-weight* when it’s hot!”

* oil weight/viscosity based on private standards that have a comparatively wide tolerance.

Especially considering changing your oil in cold months definitely shows that the oil is thicker (takes longer to change cold oil)

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[jmrtsus]

Seems like a backwards way to classify it: “here’s an oil with an undesignated viscosity but we’re telling you it acts like a 5-weight* when cold and a 30-weight* when it’s hot!”

* oil weight/viscosity based on private standards that have a comparatively wide tolerance.

Especially considering changing your oil in cold months definitely shows that the oil is thicker (takes longer to change cold oil)

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I did not set the standards the SAE did, LOL!

BTW, Conoco TropArtic was accepted after meeting mil specs as the first multi viscosity oil in the military in the late 50's. It passed both 10W and 30 weight standards with the one 10W-30 oil. Isn't chemistry great?

 

[M-Sport fan]

I did not set the standards the SAE did, LOL!

BTW, Conoco TropArtic was accepted after meeting mil specs as the first multi viscosity oil in the military in the late 50's. It passed both 10W and 30 weight standards with the one 10W-30 oil. Isn't chemistry great?

Yes it is, but they did it way back then with primitive by today's standards, polymeric viscosity index improvers which tended to shear down (and consequently actually promoted 'sludging') if you looked at them wrong.

Today's great multi grades use far better, much more sophisticated viscosity index improvers (which are much more shear-proof), and not even too many of those, since the base oils (group; 3+, 4 and 5) have improved so much, and are so 'viscosity-elastic' that they are not as needed as when multi-grades were first introduced.

 

[jmrtsus]

Yes it is, but they did it way back then with primitive by today's standards, polymeric viscosity index improvers which tended to shear down (and consequently actually promoted 'sludging') if you looked at them wrong.

Today's great multi grades use far better, much more sophisticated viscosity index improvers (which are much more shear-proof), and not even too many of those, since the base oils (group; 3+, 4 and 5) have improved so much, and are so 'viscosity-elastic' that they are not as needed as when multi-grades were first introduced.

1950's were pretty primitive.....I lived those years but oil has gotten so much better for sure! I remember even in New Orleans my dad put what I now know was thinner oil in the fall and thicker in the spring in mom's '55 Chevy and his '54 Roadmaster. Multi weights these days are soooo much better but I still change oil super frequently like my dad in the '50's and use the best oil I can find. All the top tier oils are really good but we all have our "pet" oils, LOL!

 

[M0LTEN]

I wouldn't worry about it to much. I have been running 5w30 full synthetic since my first oil change. I have 88k trouble free miles most with the mods listed. I live in south Florida were its extra crispy hot but if your uncomfortable with it just change back next oil change.