Is 5w30 "better" than it used to be compared to 10w30?

Before about 1992, the W-ratings had a completely different meaning, the CCS was measured at 0F for all grades and their were tighter thresholds for each lower W rating, then around 1992 when the J300 was updated they introduced the modern tiered system, then they lowered the temperature the MRV tests were performed at by 10C a few years later then the CCS tests were lowered by 5C a few years after that. So a 10W in the late 90s had to meet the low temperature performance that a 5W did in the early 90s.
 
I haven't seen the historically difference with "W" rating other than clueless misinformation and ol' wives tails that have been spread forever.

With conventional oils, I'd wager that the automakers, decades ago, wanted to avoid sludge caused by their interval recommendations and consumer foolishness, and wagered for the blind assumption that all 10w30's automatically have less vii/vm than all 5w30's.

There's at least one brand that sells no vii 5w30 and 10w30 oils now too. So, would a VII loaded 10w30 be better than a 5w30 without any? I doubt it.

With today's oils, and requirements from automakers and api/ilsac/acea...., its a non issue. Pick your HTHS since I don't lean on SAE grades much.

Concerning HTHS, you'd have to check the brand spec's since being a sae30, 5w30, or 10w30... only means it meets the SAE requirement. It does not mean that any grade is automatically better than any other grade concerning visc or HTHS.

The 0w30 I use is 3.5 HTHS and 12cst
The SAE30 I use is 3.1 HTHS and 10.1cst

I would have no problem trusting a modern 5w30 synthetic engine for the threadstarter's vehicles. But, I probably would use M1 ESP 0w30, Castrol a3/b4 0w30 5w30, or any 0w40 to protect the engine year round with 3.5+ HTHS. 5w30 and 10w30 can also be found with 3.5 HTHS with the HDEO and other euro specs. Plenty of good oil choices to protect the ENGINE. Too many are trying to protect everything BUT the engine.
 
My favorite M1 EP 10W-30 is perfectly fine for Western WA. It's a very good oil. Jug says 20K miles! Should do fine for my 7500 miles oci. Wal-Mart has it every time I've been there and last week had "price reduction" tag ... I already had 2 jugs in the garage so I didn't buy more. Prices seems to be on their way down so there is no rush to buy more. :ROFLMAO:
Another good option and oil that I use in my v8 is Valvoline EP 5W-30.
For my older cars I go to Kirkland or Havoline PRO-DS on sale at Wal-Mart.
 
Last edited:
I would run the 5w30, run it in all my vehicles and daughters cars year round. ;)
 
10w30 is NOT harder to find at all. I can find it at Wal Mart, Costco, Rural King, Tractor Supply and Autozone and Advance Auto Parts.
10w30 is not harder to find as a viscosity, but sometimes there are less options for it. When I go to WalMart, AZ, Napa, etc, I always see 10w30, but it is usually only found from a couple brands, not all of them. It could just be for stocking/availability reasons, but I always find more options when looking for 5w30.
 
10w30 is not harder to find as a viscosity, but sometimes there are less options for it. When I go to WalMart, AZ, Napa, etc, I always see 10w30, but it is usually only found from a couple brands, not all of them. It could just be for stocking/availability reasons, but I always find more options when looking for 5w30.
That's because 5w-30 is the best viscosity.
😉
 
Why is that? Dilution is mechanical with a low-viscosity fluid diluting a higher one. A 40-grade would be a "much better choice" in that regard.
Oil lasts about 1500 miles in a full synthetic 5w30 after which it sounds like a bunch of hammers in my Cobalt

Or about 3000-4000 on full synthetic 10w30

Have about 30,000 miles comparing each same situation 5w30 turns to garbage 10w30 lasts longer
 
Oil lasts about 1500 miles in a full synthetic 5w30 after which it sounds like a bunch of hammers in my Cobalt

Or about 3000-4000 on full synthetic 10w30

Have about 30,000 miles comparing each same situation 5w30 turns to garbage 10w30 lasts longer
Hmm okay. And the turning to garbage is due to fuel dilution?
 
Hmm okay. And the turning to garbage is due to fuel dilution?
I said dilution, the car manufacturers it’s own oil which is likely a combination of gas and antifreeze the rate and consistency varies greatly from very little (summer) to a lot (short trip’s winter )

Entire vent, egr, fuel lines and pcv system was replaced but didn’t do much.
Head gaskets seem to be ok

On 5w30 the sound is bad enough to force me to change the oil in fear it’s going to dump a basket of metallic shavings

10w30 even after having to top off twice it doesn’t get anywhere near as loud and after 30,000 miles changing oil monthly was getting very old and getting more miles out of a change was welcome 60,000 miles later no change for better or worse, fuel economy is still good. 3000-4000 mile changes are much less frustrating and at change lower noise levels is nice, have used a variety of brands but the brand doesn’t make any difference.

Have tried 5w40 but it too got noisy at about 2500 miles. Different noise but still noisy a 15w40 would probably be a different story but it randomly gets cold so that one is out.
 
I haven't seen the historically difference with "W" rating other than clueless misinformation and ol' wives tails that have been spread forever.
Some history on how SAE J300 changed with time ... not "ol' wives tails".

 
My favorite M1 EP 10W-30 is perfectly fine for Western WA. It's a very good oil. Jug says 20K miles! Should do fine for my 7500 miles oci. Wal-Mart has it every time I've been there and last week had "price reduction" tag ... I already had 2 jugs in the garage so I didn't buy more. Prices seems to be on their way down so there is no rush to buy more. :ROFLMAO:
Another good option and oil that I use in my v8 is Valvoline EP 5W-30.
For my older cars I go to Kirkland or Havoline PRO-DS on sale at Wal-Mart.
Valvoline Advanced 10W30 is also a very good 10W30 synthetic oil with a HTHS of 3.5 .
 
Subaru engines are notorious for failing, I wouldn't go down to a lower viscosity as it won't help any in avoiding failures. I would not consider mainstream 5W-30 adequate for these engines
I don’t think there’s ever been an EJ engine that won’t run fine year round on a 0/5/10w40… some years I even leave the Motul 15w50 from summer in around the calendar, and either don’t drive it or give it 3-5 min warmups if temps are below zero.
 
Back
Top