Anyone change oil weight for summer?

[headshrink]

I just joined the "synthetic club" this last weekend (Shell Rotella T 5W40). It hasn't been long enough to form any first hand opinions about the new oil, but since the oil weight is technically different than what the manual recommends (page 86), it got me thinking...... should I use a different weight for the summer? It is in the 90s this week, and I'm looking forward to a summer in the high 90s to low 100s (dreading actually is more like it).

So, I'm not intending to open old discussions on oil, but interested in what others are actually doing for the summer months.

[kkim]

according to the manual, a 40wt oil will be good till 104*F. If you regularly go above that, you might want to change to a 50wt.

[Snake]

I stick with Mobil 1 Full synthetic 10W-40 all yaer long and it gets to the 100's here in Louisiana in the summer with no problems.

[headshrink]

Would problems likely first present as overheating?

[kkim]

Originally Posted by headshrink

Would problems likely first present as overheating?

good question... dunno. no first hand experience with weather so hot. it stays pretty moderate in paradise.

[Snake]

Originally Posted by kkim

good question... dunno. no first hand experience with weather so hot. it stays pretty moderate in paradise.

Thanks for rubbing it in KKim. Onother place that I would like to visit.

[headshrink]

I hear N Korea is doing some tests this week in your direction, Kelly. Stay safe and enjoy those twisties to/from work every day

[Snake]

At least KKim is allready in heaven.

[kkim]

Originally Posted by headshrink

I hear N Korea is doing some tests this week in your direction, Kelly. Stay safe and enjoy those twisties to/from work every day

yeah, them krazy koreans!

[TheGoodLyfe]

Originally Posted by headshrink

I hear N Korea is doing some tests this week in your direction, Kelly. Stay safe and enjoy those twisties to/from work every day

LOL that's pretty messed up but funny. What is our world coming to...don't answer that. You should be alright for the summer as kkim has already said

[Banzai]

Edit: Sorry for the long post!


Lower weight/viscosity oils generally have a lower flash point than higher weight/viscosity oils, and are generally more prone to heat induced vapor loss.

So, basically, in higher ambient temps (or higher temp applications), switching to a higher weight oil for a given application will usually provide greater tolerance before viscosity/friction modifier breakdown and loss of oil volume through vapor venting. This is part of what causes sludge build up, the particles and ash that remain in dino oil after the vapors flash off alters the chemical make up of the oil at a molecular level (because, being a refined oil product, they contain many different size molecules. The smallest flash off first, and the larger ones breakdown into smaller ones, and then flash off themselves), causing the remaining mixture of thick hydrocarbons to gel and stick to the engine parts instead of flowing, acting like a blanket, keeping heat INTO the parts that they coat.

Remember, with the loss of oil volume comes the diminishing capacity for heat transfer (the lower the volume of oil to transfer a given amount of heat energy, and the faster that cycle, the less overall heat energy will be transfered, and breakdown of the oil will accelerate), and heat transfer is the secondary purpose of the oil inside of the engine in areas where heat trasnfer to the water based coolant is impossible or impractical (like the piston skirts, etc).

Think of water based coolant as the cooling system for the OUTSIDE of the engine's moving parts, and oil as the coolant for the INSIDE of the engine. Heat transfered to the oil gets transfered to the water, and both have some cross over as they radiate heat energy to the engine case and subsequently, the air.

As a side note, synthetics generally have a significantly higher flash point than same weight dino oils (cheap dinos typically flash well below 350F with premium dinos flashing about 400F, while most synths flash above 450F up to 500F), and coupled with the fact that synthetic oils, by design, are comprised of generally same size molecules, even if some synth oil burns off, what remains is chemically the same at the rest of the oil, limiting the ability of synthetics to sludge or otherwise cause harmful deposits.

So, when in hotter weather, switching to a higher viscosity heat rating (in this case a 50 over a 40) would provide added protection to the engine OIL before vapor loss, oil breakdown, and flash off, thus giving the ENGINE better overall protection for that operating environment.

The harder, and hotter, you run a given oil, the sooner it will break down, no matter what it's made of. Dino oils beging breaking down as soon as you run 'em and get progressively worse. Synthetics begin to break down as soon as they're saturated with contaminants, and drop off sharply.

All part of the give and take!

Originally Posted by headshrink

Would problems likely first present as overheating?

The first indication of a problem would be a drop in oil volume due to burn off. Oil level would drop as more was burned due to heat related viscosity breakdown, which would allow the thinner oil to burn off either through the combution chamber, or oil vapor venting out of the engine case. Sludge then begins to build up while temperature goes up, and long term damage is done to the softer and high load surfaces of your engine (read=bearings(soft) and cam lobes (high load)). The cycle would be accelerated as oil volume decreased and the heat of the engine increased.

That's why cheap oils can cause so much damage to a engine when appropriate oil change intervals aren't adhered to, they break down faster than expected, causeing chemical impurities to gel into sludge, which impedes flow and provides no protection to moving parts or heat disipation capability.

Lets take a typical 10w30 oil. Multi grade oil has a tremendous amount of additives and chemical manipulation that causes the base oil, in our example a 10 weight, to swell when heated. It has to be thin enough to NOT cause as much parasitic drag on the engine under high load start up, but has to be thick enough to provide lubrication and protection to critical engine parts. As the oil gets to operating temp, the molecules swell and thicken, until it will test as viscous as straight 30 weight oil, providing maximum engine protection. It's those chemical modifiers/molecules that cause the oil to 'swell' that break down and burn off first, followed at a slower rate by the base oil.

There is TONS of research and independant info that shows that dino oils typically loose half their viscosity in car engines about 1800-2000 miles. It's a testiment to the modern materials that the engines continue to run well under those conditions. Usually, by 3000 miles, testing shows that dino oils are at about 1/3 their 'new' rated viscosity, as well as hyper contaminated with the products of combustion and break down.

Thus, a typical mid grade (that most of us use) Havoline/Penzoil/Quaker State/Mobil 1/insert brand name here 10w30 oil, after 2K miles will test something like a 5w15, and by 3K is so contaminated and broken down it tests in the neighborhood of a 3w10. That's why an engine burns oil the more it's used, and why it's normal to have a lower volume of used oil than when you put it in new!

Research in the late 80's and early 90's discovered this, which is PART of why pre mid-90s engines had a life expectancy of only 100K miles and why oil change intervals WERE 5000 miles but are now 3000 miles for they typical auto.

Better oveall oil additive packages to prevent break down, increase heat tolerance, materials science, and advances in machine tools now let us make a better engine than ever before, but recommended oil change intervals haven't gone back up (some manufacturers recommend higher intervals in their owners manuals, but they also specify HIGHER GRADE oils with that increase!!!). Of course, there are some exceptions!

One would be the motorcycle, especially one that shared engine oil with it's gearbox and clutch.

Still wanna stick to that oil change interval as recommended?

With synthetic oils, being that they're remarkably heat tolerant compared to dino oils, changing viscosities for heat tolerance is a "try it and see" sort of thing, unless the manual for the engine/vehicle initially assumes you'll always be using synth (corvette, etc). Most manuals assume dino oil, thus different recommendations based on heat (or cold).

Short answer, I BELIEVE, in this case (and mine, too, since it's routinely in the 90s+ here from mid June until early September) that you'll be better off with the synth 5w40 than dino 10w50, and for longer. Just watch your oil consumption. If it starts to increase over your 'cooler environment' useage for that machine, that would be the time to investigate changing viscosity or quality of oil, be it dino or synth.

And the final answer for best protection, as recommended by so many independant researchers, is chaning the oil NOT LATER THAN every 3K miles (for dino). They're a bit more disjointed on their recommendations on synth, but I've never seen it recommended to go as long as the synth manufacturers recommend, and never more than 5K, and NEVER the hype of 'double the oil change interval' that was so prevalent in early sales literature for synth oils.

Bottom line, though, is that changing the oil more often, but within reason, is the best protection.

[headshrink]

Thanks Banzai, I always enjoy your posts.... fills the head with knowledge

[stealth250]

I've used Valvoline 4 stroke 20W50 since my first oil change. I changed it at 500 mile intervals in the first 1,500 miles. Then at 2,500. I plan on doing an oil service every 1,000 miles. I have 3,300 on it now. May seem like overkill to some, but you can't change it too often in my opinion. I also have been using the Wix #24941 filter at every change.
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[kkim]

Mike,
Just curious... why do you use a 50w oil?

[stealth250]

Originally Posted by kkim

Mike,
Just curious... why do you use a 50w oil?

Old school drag racer mentality, I guess.
With the hot temps, small oil capacity and high rpm's, I figure a heavier weight oil will handle those conditions a little better than 10w40. I don't ride in the cold (below 60 deg.) usually, and when I checked the manual's recommendations, I believe 20w50 falls in a pretty wide ambient temp range. Summer months can be in the 90's here in Indy (like today). I tend to be a little over cautious (anal) about engine service/tuning, and I've always had great longevity and wear in drag engines with 20w50.

Other than that...I have no idea!

[stealth250]

My other "Ebony" ride...

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[headshrink]

I went to buy the Wix filter last week from NAPA/Riebes. They said they don't have it anymore but instead gave me the NPS (Napa Powers Sport) Filter Part #PS4941 for $6.69 (includes O rings). They said it is made by Wix, so is essentially the same thing. I'm fine with that, but wonder if products are slightly better when they carry their own name.... as long as it isn't a Fram I guess.

[stealth250]

Originally Posted by headshrink

I went to buy the Wix filter last week from NAPA/Riebes. They said they don't have it anymore but instead gave me the NPS (Napa Powers Sport) Filter Part #PS4941 for $6.69 (includes O rings). They said it is made by Wix, so is essentially the same thing. I'm fine with that, but wonder if products are slightly better when they carry their own name.... as long as it isn't a Fram I guess.

Yes, all NAPA filters are made by Wix. I've used them as well and they appear to be the same filter. If you prefer Wix, you can get them at O'Reilly Auto Parts. But, I had to "get in the Zone" to get the Valvoline 4 stroke oil.

[headshrink]

Originally Posted by stealth250

Yes, all NAPA filters are made by Wix. I've used them as well and they appear to be the same filter. If you prefer Wix, you can get them at O'Reilly Auto Parts. But, I had to "get in the Zone" to get the Valvoline 4 stroke oil.

I "got in the zone" last time, but went to wally world this time for the switch to Rottela.

[TonyKZ1]

I use the Rotella synthetic 5w40 all year long, it really helped my old air cooled '75 KZ400 start easier in the winter. So after I got the 250, I started using the 5w40 all the time too.
Tony