Engine oil viscosity

[bononos]

Does it make sense to change the oil to a higher viscosity once the car racks up over 75k miles? Manual states 10W30 on my commute car, no winters.

 

[slugg]

No.

 

[Jimzz]

What year, make, and model?

I run 5w30 in all my cars/trucks no matter the mileage unless it has other major issues. I do use the high mileage oil in my truck but that's it.

 

[slugg]

Hm... Where should I begin...

The manual, specced out by engineers, says to use 10w30. The only time manufacturers recommend a different viscosity is for different climates or possibly different applications. But since you said that the car isn't driven in winters and you're only commuting, neither of these conditions are met.

And if you were an engineer and had a specific reason for a change in oil viscosity, I really doubt you'd be asking us here.

You only see people using different oils when they start to experience wear-and-tear issues from high mileage. At 75k miles, I strongly doubt this is the case. Maybe somewhere around 120k+, but even then, your mileage may vary.

So... My original answer of "no" still stands.

 

[disappoint]

^ What he said. 75k miles isn't even that much.

 

[996GT2]

The manual, specced out by engineers, says to use 10w30. The only time manufacturers recommend a different viscosity is for different climates or possibly different applications. But since you said that the car isn't driven in winters and you're only commuting, neither of these conditions are met.

It should be noted that sometimes manufacturers change oil recommendations based on MPG figures that they're trying to hit. For example, Honda has been gradually phasing in 0W-20, probably in an attempt to eek out a bit of MPG gain:

 

[SparkyJJO]

No sense to increase from what is called for, especially at that low of mileage. My vehicle calls for 5W-30, and at 196k miles I'm still using 5W-30. No reason to use anything else.

 

[Jeff7181]

I agree. No reason to change, especially on a commuter car.

If you're talking about a high performance engine, especially if forced induction is used, I'd probably use synthetic oil, but wouldn't change the viscosity.

Only time I'd ever change the viscosity is in extreme cold conditions. I'd probably use 0w20. The first number means the oil acts like a SAE 0 oil at cold temperatures. The second number means the oil acts like a SAE 20 oil at 100 degrees C. The benefit of having an oil that flows better when cold would outweigh the potentially problems caused by having an oil that's too thin at high temperatures.

From what I remember, the way a multigrade oil such as 0w20 is made is a SAE 0 oil has viscosity modifiers added to it to make it act like a SAE 20 oil at 100 degrees C. So what you need to remember is that as the oil ages and the additives break down, your oil will start to act more like a SAE 0 oil at higher temps and potentially won't provide proper lubrication once the engine warms up. This could be dangerous in a turbocharged engine where the oil sees higher peak temperatures than a naturally aspirated engine.

 

[Slickone]

You could go to synthetic (if not already using or high mileage oil if you're just wanting an improvement. What kind of car?

 

[tortillasoup]

I wouldn't increase the oil viscosity in most cases. You especially don't increase it if the vehicle isn't experiencing any issues. If you do change the viscosity, the one number you can change w/o risk is the "xW" number. So if the car says 5W-30, you can safely change to 0W-30, if it says 20W-50, you can use 0W-50. I haven't had any luck with the oil viscosity reduction of the second number so on my Camry/Es350, lexus says I can use 0W-20 but the car was first specc'ed with 5W-30. I found that using 0W-20 counter-intuitively hurt the gas mileage of the car so I went back to 0W-30 which returned the fuel economy to what it was.

 

[C1]

10W - 30 should be okay.

Had a Corolla exclusively used by the wife and the dealer was putting in 5w-30. My wife drives hard and I noticed that the dip stick was getting quite shellac like looking. Had a bitch of a time even steel wooling off the beige colored deposit. Also seemed to be getting lots of blow-by (based on oil getting dirty soon after dealer change).

Conclusion is that the Toyota dealer's crappy bulk oil was breaking down (heat + mechanical pressure) resulting in creating problematic engine deposits.

Changed own oil to Valvoline 10w - 30 and ALL issues disappeared. Oil stayed noticeably cleaner much longer.

So there you have it.

Change the oil, change wife or change the vehicle - your pick.

 

[tortillasoup]

The color of the oil isn't a guarantee of anything. If you actually want to know, you have to do a used oil analysis because for all we know, the detergents in the oil were doing their job compared with the new stuff. Also who is to say using 5w-30 Valvoline also wouldn't have yielded the same results?

 

[C1]

No thanks.

With the change to Valvoline, the reduction in mechanical engine noises (eg, valve lash, rod, piston and internal engine gearing sounds) was quite discernible when having to start out cold and climb an up hill grade.

 

[Kelvrick]

No thanks.

With the change to Valvoline, the reduction in mechanical engine noises (eg, valve lash, rod, piston and internal engine gearing sounds) was quite discernible when having to start out cold and climb an up hill grade.

How reputable is the dealer? Do you even think they were using the right/new oil? If it was a random lube shop, I'd ask if you're sure they even changed anything.

 

[tortillasoup]

No thanks.

With the change to Valvoline, the reduction in mechanical engine noises (eg, valve lash, rod, piston and internal engine gearing sounds) was quite discernible when having to start out cold and climb an up hill grade.

I bet the dealer uses Mobil 1. I've heard of people reducing valvetrain noise when they switched from Mobil 1 to Valvoline so I believe what you're saying. However I'd try and use a 5W or 0W- formula instead of a thick 10W formula so that you get better flow on cold start.