View Full Version : When to use detergent oil…


snorky18
04-05-2011, 07:48 AM
When to use detergent oil…

Assumptions:
Detergent oil suspends contaminants in the oil. If the vehicle has an oil filter, it will remove the contaminants from the oil. Non detergent oil allows the contaminants to settle to the bottom to some extent.

My thoughts on when to use it (based on a lot of reading and zero practical experience):

Engines that have no oil filter (typical small engines, mowers etc.) – use a non-detergent oil (typically SAE 30) so that you don’t have contaminants suspended in your oil indefinitely and being recirculated through the engine. Non-detergent also makes sense for air compressors.

Engines that do have an oil filter – use a “regular” (detergent) motor oil, as the contaminants will be filtered out by the oil filter and keep the engine cleaner.

What is confusing to me:
My air compressor (Kobalt 60 gallon 150 psi ~3hp) has a sticker on the side that reads “This compressor requires fully synthetic 10w-30 motor oil”. Obviously that oil will have detergents in it. This bothers me b/c
A) Contaminants in the oil will be recirculated constantly b/c they are suspended in fluid
B) The compressor never gets hot enough to get to take advantage of 30W, so essentially it performs as a 10W oil the entire time.

The Questions:
Why my air compressor, which produces no combustion byproducts, and runs at relatively low (close to room) temperatures, would need a fully synthetic 10W-30 engine oil? (Based on my assumptions of detergent oil suspending contaminants, would result in contaminants being recirculated).

Why Briggs and Stratton allows the use of 5w-30 motor oil (which has detergents, so same issues as mentioned previously) in their small engines, even when the engine will never be operated below 50°F?

Am I over thinking this? Go ahead, fire away, I’d welcome any feedback.

wormwood
04-05-2011, 08:23 AM
...Am I over thinking this? .....

Yes.

Use what they say and be happy. :)

sberry
04-05-2011, 08:30 AM
Engines that have no oil filter (typical small engines, mowers etc.) – use a non-detergent oil (typically SAE 30) so that you don’t have contaminants suspended in your oil indefinitely and being recirculated through the engine. Where is that written? Most of these engines recommend 30 wt detergent oil, detergents for engines, non for non combustion.

sberry
04-05-2011, 08:34 AM
I wouldnt mind seeing a manual where non is recommended and not one 60 yrs old.

wormwood
04-05-2011, 08:34 AM
Where is that written? Most of these engines recommend 30 wt detergent oil, detergents for engines, non for non combustion.

I have a gasoline power washer that specifically calls for nondetergent 30 weight FWIW.

38Chevy454
04-05-2011, 09:24 AM
The detergent oil also helps prevent sludge build-up. You are way overthinking this. Just change your oil at reasonable intervals and you will never have any oil related problems, regardless of what oil type you use.

Aberdale
04-05-2011, 09:36 AM
Snorky, I have long understood the need for non-detergent for non-filtered engines, and detergent oil for filtered engines. I was taught that when I was younger as well.

I have since decided that the benefits of detergent oil can also benefit non-filtered engines by allowing those dirt particles to be drained as part of an oil change. Who wants those particles to continue taking residence in the engine any more than they need to? After a while some of it is bound to break loose and make it's way through the oil passages anyway.

Besides, most detergent oil also come with superior anti-corrosion and anti-wear additives that often aren't in single weight non detergent oils. Frequent oil changes in non-filtered engines are a no brainer when you think about it. So I have ended up using multi-viscosity detergent oil in just about everything to simplify things. I just use three different weight viscosities (0W-40, 10W-30, and 15W-50) that covers everything I own.

YMMV.

wormwood
04-05-2011, 09:54 AM
Snorky, I have long understood the need for non-detergent for non-filtered engines, and detergent oil for filtered engines. I was taught that when I was younger as well.

I have since decided that the benefits of detergent oil can also benefit non-filtered engines by allowing those dirt particles to be drained as part of an oil change. Who wants those particles to continue taking residence in the engine any more than they need to? After a while some of it is bound to break loose and make it's way through the oil passages anyway.

Besides, most detergent oil also come with superior anti-corrosion and anti-wear additives that often aren't in single weight non detergent oils. Frequent oil changes in non-filtered engines are a no brainer when you think about it. So I have ended up using multi-viscosity detergent oil in just about everything to simplify things. I just use three different weight viscosities (0W-40, 10W-30, and 15W-50) that covers everything I own.

YMMV.
What do you put the 0W-40 in?

bradweingartner
04-05-2011, 10:19 AM
What do you put the 0W-40 in?

I run this in my Audi. Many European cars call for this weight.

sberry
04-05-2011, 07:53 PM
I have a gasoline power washer that specifically calls for nondetergent 30 weight FWIW. What engine is in it? I looked at a Briggs manual, don't have older ones but they say detergent oil, I have seen pressure washers use non in the pump.

trainer
04-05-2011, 08:44 PM
I know a few guys who seem to think that "single weight" is the same as "non detergent"

One guy has a Yamaha generator that calls for SAE 30 weight. He has always used non detergent because "that's what #30 oil is"

The only thing that i've ever seen that specifically calls for non detergent oil is the oil cups on electric motors.

Kev442
04-05-2011, 09:21 PM
My lawnmower has been run in sub 40 degree temps. I keep it super short in the fall to discourage the voles from chewing up the lawn under the snow. It takes a heck of a haul on the cord to pull it over and that's after letting the sunlight warm it up for 15-30 minutes!

snorky18
04-11-2011, 08:44 AM
Snorky, I have long understood the need for non-detergent for non-filtered engines, and detergent oil for filtered engines. I was taught that when I was younger as well.

I have since decided that the benefits of detergent oil can also benefit non-filtered engines by allowing those dirt particles to be drained as part of an oil change. Who wants those particles to continue taking residence in the engine any more than they need to? After a while some of it is bound to break loose and make it's way through the oil passages anyway.
YMMV.

Glad to hear someone else was fed the same kool-aid as me about the non-detergent for non filtered engines though. :)

After some more research, I think I'm going to stick with detergent oil for everything except the air compressor.

justanengineer
04-11-2011, 10:51 AM
I run this in my Audi. Many European cars call for this weight.

Is that for extreme cold weather conditions (like nothing we see in the continental 48)?

When I was still in the Army stationed in Alaska we used 0W30 in engines, but had to change it out for 10 or 15w30 once ambient temperatures got above freezing with any regularity as it caused serious damage to bearings. Cant speak for gasoline engines, but would never run 0w in any diesel in warm weather.

Regarding detergent vs non...I use detergent unless the machine specifically calls for non, but most of my toys and tools are 40+ yrs old and in all cases, any oil is better than none.