Startup question as it relates to 0w20 vs 5w30

[kschachn]

True, but that is about all a typical consumer has available to look at. A VOA will most likely be from a different lot, or formulation, than the jug someone grabs off the shelf at Walmart.

That might be better than basing it off of the unknown of a PDS.

However, I wouldn't base oil choice off of a $30 spectrographic analysis either. I'm not capable of reading the tea leaves of dissociated compounds and predicting future performance. But at the same time neither am I able to do so off of a PDS or SDS. Perhaps you are.

 

[Brian123]

Ok. I have to explain something, and ultimately I have a question at the end.

I will try and help you out with your question, but Pablo will give you a better answer, lets not forget Patman!

I decided, to use 5w30 INSTEAD of 0w20 for my new 2025 CX 5 Skyactive engine NON turbo. It calls for 0w20 , but due to cafe standards and many opinions, i went with 5w30 on my first oil change.

Good Choice.

I live in Texas where its cold now but NOT brutal winters.

In the good old USA, the weather is not cold enough to tell the difference between 0W-20 and 5W-30!

My reason for switching to 5w30 is because its supposedly provides slightly more wear protection overall, based on my research.Better for engine, not for cafe standards type of thing.

If the 5W-30 has a higher HTHS Number than the 0W-20, you have a point!

Having said all that, here is my question:

If it is true that 90 percent of engine wear occurs at STARTUP, and 0w20 gets to the engine QUICKER at startup, doing the math, does not this make the 0w20 a better choice then, no matter what tests show 5w30 is better overall (while driving etc)?

I am sure Pablo, and others will chime in here, there is a certain temperature, meaning a low temperature where 0W-20 flows or travels around your engine quicker than 5W-30, it is not happening in Texas!

 

[fordtough]

Thats really interesting.. I bet the engines are quieter.. and is this in areas that get really cold?

Austrai

 

[fordtough]

I’m in houston I run 5w30 in my wife’s 2016 Honda accord and my 2011 Lexus is250 no issue 0w20 is for fuel economy.

 

[4wd]

All in signature came with 0W-20 and kicked the habit

 

[CleanSump]

It won't make any difference when the third or fourth owner has it towed to the junkyard. It won't be cold starts with 5W-30 vice 5W-20 that put it there.

 

[Carlostrece]

Some of this is subject to opinion. If your new car is parked outdoors in winter, then I recommend using 0w20 in winter. If parked in a heated garage, then 5w20 in winter.

In summer I recommend 5w20 or 5w30 for you. In your shoes with new car I'd probably use 5w20, but 5w30 would be fine too.

For fall and spring, 5w20.

If you want to keep it simple and use 1 oil year round, then 5w20, IMO.

Use a Full Synthetic oil. There's planty of good affordable ones at Walmart.

Also consider this... Valvoline Extended Protection Full Synthetic is thick per grade. Even moreso with Quaker State Ultimate Protection Full Synthetic. So a 0w20 in those oils is respectably thick at full op temp. Almost like a 0w24. A 5w20 in those oils is even a bit thicker yet. Almost like a 5w27.

Those ^ oils are affordable at Walmart.

If you use a 5w30, then choose a brand that is thin per grade. I won't bother to lost those here because I don't remember them all, but they do exist. Pennzoil Ultra Platinum is one that I do remember is thin per grade. So if you used 5w30 Pennzoil Ultra Platinum, that'd be a good choice for year round, especially since it's a GTL oil, which is known to perform well at cold start (even in 5w30).

Others opinions may vary.

 

[FZ1]

On cold start no, the 90% figure is exaggerated. On hot start with thin probably but even then not that high percentage wise. Thicker oil reduces startup wear as the residual film provides more separation and as long as it still pumps good which a 0w-30 like ESP will especially in the not awful texas winters you can switch. But if you change your mind stellar 0w-20's like Mobil 1 ESP, Pennzoil Ultra Platinum and Castrol EDGE Extended Performance are better than what the dealer would put in. And the 30 grades of those three are better still.

Here's a good thread on that, shame it got locked so soon. TWX summed it up better than I could.

T

Post in thread 'Effects of start-stop tech on bearings = more wear'

Oct 4, 2025

Engine is off, oil pressure goes to zero. Then re-start a minute later ??? It's like doing "dry starts" all the time IMO. Has to be added wear on bearings due to no oil pressure.

The increase in wear isn't due to the lack of oil pressure. There's enough oil in the bearing to provide lubrication until the bearings get oil pressure again after a second or so.

The wear is due to the fact that hot oil is too thin to provide hydrodynamic lubrication at very low rotational speed, like when the engine first starts cranking, which results in some brief metal on metal contact.

Here's...

• twX

• 
• 

Good reference! Thanks!

 

[Patman]

Some of this is subject to opinion. If your new car is parked outdoors in winter, then I recommend using 0w20 in winter. If parked in a heated garage, then 5w20 in winter.

In summer I recommend 5w20 or 5w30 for you. In your shoes with new car I'd probably use 5w20, but 5w30 would be fine too.

For fall and spring, 5w20.

If you want to keep it simple and use 1 oil year round, then 5w20, IMO.

Use a Full Synthetic oil. There's planty of good affordable ones at Walmart.

Also consider this... Valvoline Extended Protection Full Synthetic is thick per grade. Even moreso with Quaker State Ultimate Protection Full Synthetic. So a 0w20 in those oils is respectably thick at full op temp. Almost like a 0w24. A 5w20 in those oils is even a bit thicker yet. Almost like a 5w27.

Those ^ oils are affordable at Walmart.

If you use a 5w30, then choose a brand that is thin per grade. I won't bother to lost those here because I don't remember them all, but they do exist. Pennzoil Ultra Platinum is one that I do remember is thin per grade. So if you used 5w30 Pennzoil Ultra Platinum, that'd be a good choice for year round, especially since it's a GTL oil, which is known to perform well at cold start (even in 5w30).

Others opinions may vary.

5w-20 is one of those viscosities that is almost obsolete as well though. It really doesn’t offer any benefits over 0w-20. So just use 0w-20 and forget about the 5w-20. Any application that called for 5w-20 originally can use 0w-20 instead.

 

[cheesepuffs2]

Some of this is subject to opinion. If your new car is parked outdoors in winter, then I recommend using 0w20 in winter. If parked in a heated garage, then 5w20 in winter.

In summer I recommend 5w20 or 5w30 for you. In your shoes with new car I'd probably use 5w20, but 5w30 would be fine too.

For fall and spring, 5w20.

If you want to keep it simple and use 1 oil year round, then 5w20, IMO.

Use a Full Synthetic oil. There's planty of good affordable ones at Walmart.

Also consider this... Valvoline Extended Protection Full Synthetic is thick per grade. Even moreso with Quaker State Ultimate Protection Full Synthetic. So a 0w20 in those oils is respectably thick at full op temp. Almost like a 0w24. A 5w20 in those oils is even a bit thicker yet. Almost like a 5w27.

Those ^ oils are affordable at Walmart.

If you use a 5w30, then choose a brand that is thin per grade. I won't bother to lost those here because I don't remember them all, but they do exist. Pennzoil Ultra Platinum is one that I do remember is thin per grade. So if you used 5w30 Pennzoil Ultra Platinum, that'd be a good choice for year round, especially since it's a GTL oil, which is known to perform well at cold start (even in 5w30).

Others opinions may vary.

What’s the point of running a 5W when you could run 0W all year round?

 

[Carlostrece]

What’s the point of running a 5W when you could run 0W all year round?

What I'm about to say used to be the case in past decades regarding shear stability and viscosity stability. I'm not sure how much it still applies in 2025 because oils are better than they used to be. Specifically shear stability and viscosity improvers are better than used to be.

A wider viscosity range means a thinner base oil with more viscosity improver chemicals. That's fine when the oil has low miles, but when the oil gets more mileage on it, the viscosity improvers get sheared and viscosity gets lower. This is more of a concern in a hot climate (OP lives in Texas). Also more of a concern with a direct injected engine because fuel dilution is an additional factor thinning the oil.

5w20 is (theoretically) more shear stable than 0w20. So 5w20 would have better op temp viscosity when oil has 4K or 5K+ miles of use.

In the same way, 10w30 is (or was) more shear stable than 5w30. 5w40 is more shear stable than 0w40. And so on.

The above was certainly true 30-20 years ago. Oils have improved a lot in 20 years, especially in shear stability. So I'm sure it's less of a concern/issue in 2025 than it used to be. However, I think it still matters somewhat. So if climate/season is appropriate for 5w20, then it still has its uses.

In this case, he lives in Texas with hot summers and probably has a direct injected car. So in summer, I recommend 5w20 in a brand that runs thick per grade (Valvoline Extended Protection Full Synthetic or Quaker State Ultimate Protection Full Synthetic for examples), or a 5w30 in a brand that runs thin per grade (Pennzoil Ultra Platinum).

He can use a 0w20 in any season or year-round if he wants to, but if he does that, then I suggest using a brand that is thick per grade (Valvoline Extended Protection Full Synthetic or Quaker State Ultimate Protection Full Synthetic for examples).

 

[cheesepuffs2]

What I'm about to say used to be the case in past decades regarding shear stability and viscosity stability. I'm not sure how much it still applies in 2025 because oils are better than they used to be. Specifically shear stability and viscosity improvers are better than used to be.

A wider viscosity range means a thinner base oil with more viscosity improver chemicals. That's fine when the oil has low miles, but when the oil gets more mileage on it, the viscosity improvers get sheared and viscosity gets lower. This is more of a concern in a hot climate (OP lives in Texas). Also more of a concern with a direct injected engine because fuel dilution is an additional factor thinning the oil.

5w20 is (theoretically) more shear stable than 0w20. So 5w20 would have better op temp viscosity when oil has 4K or 5K+ miles of use.

In the same way, 10w30 is (or was) more shear stable than 5w30. 5w40 is more shear stable than 0w40. And so on.

The above was certainly true 30-20 years ago. Oils have improved a lot in 20 years, especially in shear stability. So I'm sure it's less of a concern/issue in 2025 than it used to be. However, I think it still matters somewhat. So if climate/season is appropriate for 5w20, then it still has its uses.

In this case, he lives in Texas with hot summers and probably has a direct injected car. So in summer, I recommend 5w20 in a brand that runs thick per grade (Valvoline Extended Protection Full Synthetic or Quaker State Ultimate Protection Full Synthetic for examples), or a 5w30 in a brand that runs thin per grade (Pennzoil Ultra Platinum).

He can use a 0w20 in any season or year-round if he wants to, but if he does that, then I suggest using a brand that is thick per grade (Valvoline Extended Protection Full Synthetic or Quaker State Ultimate Protection Full Synthetic for examples).

I know where you’re coming from and used to agree with that general thinking too, but it depends on the type of VII that’s used, and also, in reality it just doesn’t make a difference imo for reasonable OCIs.

 

[Titan]

What I'm about to say used to be the case in past decades regarding shear stability and viscosity stability. I'm not sure how much it still applies in 2025 because oils are better than they used to be. Specifically shear stability and viscosity improvers are better than used to be.

A wider viscosity range means a thinner base oil with more viscosity improver chemicals. That's fine when the oil has low miles, but when the oil gets more mileage on it, the viscosity improvers get sheared and viscosity gets lower. This is more of a concern in a hot climate (OP lives in Texas). Also more of a concern with a direct injected engine because fuel dilution is an additional factor thinning the oil.

5w20 is (theoretically) more shear stable than 0w20. So 5w20 would have better op temp viscosity when oil has 4K or 5K+ miles of use.

In the same way, 10w30 is (or was) more shear stable than 5w30. 5w40 is more shear stable than 0w40. And so on.

The above was certainly true 30-20 years ago. Oils have improved a lot in 20 years, especially in shear stability. So I'm sure it's less of a concern/issue in 2025 than it used to be. However, I think it still matters somewhat. So if climate/season is appropriate for 5w20, then it still has its uses.

In this case, he lives in Texas with hot summers and probably has a direct injected car. So in summer, I recommend 5w20 in a brand that runs thick per grade (Valvoline Extended Protection Full Synthetic or Quaker State Ultimate Protection Full Synthetic for examples), or a 5w30 in a brand that runs thin per grade (Pennzoil Ultra Platinum).

He can use a 0w20 in any season or year-round if he wants to, but if he does that, then I suggest using a brand that is thick per grade (Valvoline Extended Protection Full Synthetic or Quaker State Ultimate Protection Full Synthetic for examples).

Unless you are cherry-picking a No VII oil such as offered by HPL, MOST 0w20 base oils are superior to MOST 5w20 base oils. 0w20's are for the most part certainly NOT thinner than a typical 5w20 with regard to viscosity at operating temp, or at HTHS temps.

 

[Carlostrece]

I know where you’re coming from and used to agree with that general thinking too, but it depends on the type of VII that’s used, and also, in reality it just doesn’t make a difference imo for reasonable OCIs.

I agree that reasonable OCI (or lack of) is a key factor. Climate/heat is another key factor. The OP lives in Texas, which IME is brutally hot in summer. Unfortunately TX can also be very cold in winter. Thus his oil choice is a challenge if he wants to use same grade/viscosity year-round. IMO

 

[Carlostrece]

Unless you are cherry-picking a No VII oil such as offered by HPL,

No boutique oils for me.

MOST 0w20 base oils are superior to MOST 5w20 base oils. 0w20's are for the most part certainly NOT thinner than a typical 5w20 with regard to viscosity at operating temp, or at HTHS temps.

You're probably correct in regard to new oil. However, I'm skeptical that a 0w20 after 4-5K miles in brutal TX summer heat will still have as high op temp viscosity or HTHS as 5w20 of same brand.

If they have equal quality base oil, then I'm correct. If the 0w20 has better base oil, then you may be correct. So you might be correct in 2025 (at least with some brands). In past decades what I said would have been correct for sure. I'm not sure who's correct in 2025. I think it might depend on which brand(s) of oil we're talking about.

 

[Titan]

No boutique oils for me.

You're probably correct in regard to new oil. However, I'm skeptical that a 0w20 after 4-5K miles in brutal TX summer heat will still have as high op temp viscosity or HTHS as 5w20 of same brand.

If they have equal quality base oil, then I'm correct. If the 0w20 has better base oil, then you may be correct. So you might be correct in 2025 (at least with some brands). In past decades what I said would have been correct for sure. I'm not sure who's correct in 2025. I think it might depend on which brand(s) of oil we're talking about.

VOA's and used oil analysis will show the newer 0w20 oils are indeed, as a whole, superior to the old 5w20's.

 

[Carlostrece]

VOA's and used oil analysis will show the newer 0w20 oils are indeed, as a whole, superior to the old 5w20's.

What about new 5w20 oils?

For mainstream oils sold in Walmart and autostores, you may be correct in regard to most brands. With some boutique oils, 5w20 might still be more shear stable than 0w20. However, few people buy boutique oils. I haven't bought any boutique oil yet. Though I might if I needed a Xw20. I only buy 5w30 because the vehicles I maintain are older.

 

[Titan]

What about new 5w20 oils?

For mainstream oils sold in Walmart and autostores, you may be correct in regard to most brands. With some boutique oils, 5w20 might still be more shear stable than 0w20. However, few people buy boutique oils. I haven't bought any boutique oil yet. Though I might if I needed a Xw20. I only buy 5w30 because the vehicles I maintain are older.

No engine "needs" a 5w20 vs a 0w20.

 

[tolian21]

5w-30 was used for decades in northern climates before another CAFE tightening, none of those old engines got destroyed by cold start. 5w-30 is fine

 

[leeaspell]

I use 5w30 in my truck in northern Alberta years round, temps down to -45, as do many other people. I don't think we have a higher proportion of engine related failures as compared to warmer areas. Granted at those temps most people as using at least a block heater