Originally Posted By: bchannell
This question comes up from time to time on here, and there always seems to be a lot of misconceptions about oil use in small engines.
First, remember the most important piece of information on this issue is that for years and years, and thousands upon thousands of hours of use, these same small engines ran on 30HD oil, add to that, the fact that a heck of a lot of people didn't do the correct maintenance, or in a lot of cases, no maintenance at all, and they still ran, for years, and years and years. Now, just to go a bit further with this, almost any oil from straight 20W to 20W50, and EVERYTHING in between has been used (or misused, as the case may be) and still these engines ran, and ran. Are you starting to get the picture? These engines are tough and reliable with almost anything in the sump. So, to answer your question, in the strictest sense, NO, you do not need synthetic oil.
Now, most of the guys who come here, are out for some more in the way of information. Some want to save as much money as possible, some want to protect their engines with nothing but the best, no matter the cost, and others just want as much protection as they can get without mortgaging the farm. We all have differing points of view, and come from different directions. Synthetic oil will handle the temperatures of air cooled engines better than dino oil. HDEO oils will also handle heat better, and they are much cheapter than syns. It's hard to beat the ability to stay in viscosity that 30HD has, but then again, 15W40 HDEO is also pretty good in that regard. So you see, the "BEST" is all in what you consider important.
If money is no object, it would be hard to beat oils like Mobil 1 HM, Rotella T6, and any such heavy duty oils. I am of the opinion that highly expensive boutique oils are neither worth the cash or the effort to fool with. I do, however, think that a "slightly" higher level of Zddp is a good thing for small engines. I don't think it's necessary to go to the motorcycle oils or racing oils with their 1500ppm+ levels, but something with 1000-1300ppm seems just right. You can go with higher priced oil, but it then seems to come to the point of diminishing returns. These oils would be, to my mind, the very best protection, anything in the 5W30 to 15W40 range that you feel comfortable with.
If you don't go the above route with syn oil, then you are ok to use almost anything in the same viscosity range in dino oils and I gotta tell you, it'll last a long time.
What's the difference between using the two extremes of oils over a period of time, who knows? but I bet the difference is not huge, but noticeable. That difference is what fuels the discussions here, and if you can answer that question, you're a genius.
You've made a number of good points. However, I will take exception to the longevity statement of those old engines running straight 30. An objective look at engine lifespan measured in hours is required. Mowers powered by Briggs engines, 30W oil and used in seasonal service may accumulate as much as 25 hours per year, often quite less. 250 hours over 10 years really is not much. It's no wonder these engines "Seem" to last forever. Objectively, those same engines wear out early when used for tasks requiring continuous use. Such as construction generator use, continuous duty water pumps and so on. Low end lawn mower type engines are NOT robust, long life engines. A practical maximum is often 250 hours. The EPA backs up my point with a emissions rating system that clearly lists low end engines as emissions compliant for 25% of the time of the higher end equipment.
I have 2 FL acres and 12 harsh TN acres. My equipment gets used extensively. Since I demand performance from my OPE, much of which is not "high end stuff" , I've learned to use quality synthetic oil and change it often. It simply eliminates problems with continuous duty engines, doing heavy work, in hot conditions.
I agree with your choices of oils.
