Ordinary VS Synthetic Oil

Dear Car Talk,

My 2007 Toyota Tacoma’s oil change is coming soon. It now has 165,000 miles. All this time, I have been using ordinary oil. For the next oil change, I want to switch to Mobil 1-10w-30 Synthetic Oil. Would this switch ruin the engine? What is the difference anyway?

It would not ruin… or help… the engine in any way. All it will do is cost more.

“Dino” and synthetic oil are chemically the same. The only differences are that synthetic contains fewer impurities and its molecular size is allegedly more consistent. Purity matters when oils are subjected to extreme heat, and some feel that molecular consistency matters when the oil is subjected to extreme cold. That matters to people who have turbochargers, and to people in Barrow Point Alaska, but '07 Tacomas did not come with turbochargers and if you lived in Barrow Point you’d already know about this stuff.

Happy motoring.

The synthetic oil of the required viscosity for your engine won’t do any damage, but whether it is worth the added expense over non-synthetic oil is another question. You can switch back and forth from synthetic to non-synthetic on an engine that does not require synthetic. As for cost, my local Rural King store sells its housebrand RK full synthetic for $2.79 a quart. Its 0W-20 meets all the specs for my 2011Toyota. I splurged and bought a quart of 10W-30 RK synthetic for my lawnmower that I bought in 1988. It cut the oil consumption by 75% over the straight 30 weight detergent I had been using. I think the myth about switching to synthetic oil goes back to the 1950s when switching from non-derergent to detergent caused problems. My dad switched his 1949_Dodge from non detergent to detergent and the oil consumption, increased dramatically. That Dodge became a real oil hog.

I see no reason to change to synthetic. Use what you’ve been using, and enjoy your vehicle’s long life.

Just stick to the viscosity your manual calls for, and that is probably 5W30. unless you live in a very hot area, 5W30 is by far the better choice than 10W30…

Most newer vehicles need 5W20 or 0W20 to meet he more stringent fuel mileage standards.

My 2007 Toyota uses 5W30 but 5W20 is OK as long as it is synthetic. A very light oil in an older vehicle may cause oil consumption although it will still be a good lubricant.

As pointed out, if you go to synthetic, pick a quality product like Mobil 1, and carefully monitor your oil level.

Is 10W30 what’s recommended by Toyota for your vehicle? It may be that, even if 10W30 was recommended, sometime after 2007 they have retroactively recommended something else - maybe 5W20 - instead.

I agree no harm in going to synthetic, except the economics of it.

If it were my van, I’d stick with the mineral oil you have been using. We have a van with 160,000 and a sedan with 156,000 miles and have always used mineral oil, and I don’t plan to switch.

This post makes me wonder several things: A - why think about changing what you have been doing after this much time B - did someone recommend changing to synthetic C - did someone tell the OP that changing to synthetic would ruin the engine

For the record, I have 235,000 and counting on my Scion with no problems. The only non-maintenance item I’ve had to replace was the alternator, a caliper, and the struts… and I did the struts just “because”. And I’ve only used dino.

My '89 Toyota pickup (they hadn’t come up with the “Tacoma” name yet) had 338,000 miles on it when it got totaled… and it never head the head off and still only burned a qt every 1,200 miles. I only used dino.

My '79 Toyota pickup I had for 11 years before the frame rotted out. Didn’t pay attention to the miles. It still ran great, and the junkyard owner I gave it to bolted the cab to the bed and used it for a yard truck. I only used dino.

If I had a vehicle that required synthetic, I’d use it. But none of my many Toyotas ever did. So I never did.

I wouldn’t switch as long as what you’ve been using meets Toyota’s recommendation for this vehicle. It would probably be ok and cause no problems but you run the risk of incompatibilities in the additives. That’s why it is best to stay with the same brand of oil, choose one brand and stick with it in other words. If you do switch to synthetic, suggest to stick w/the same brand as the dino oil you’ve been using. Both my vehicles, one 20+ years old, another 40+ years old, both have over 200 K running on dino oil, and never any lubrication related problems to date. I’ve always stayed with the same brand, Pennzoil.

Some posters here have suggested when switching to synthetic, its a good idea to change the oil again soon after the switch. The synthetic oil picks up stuff and places it into solution that the dino doesn’t.

In my older vehicles, I use the oil brand called “On Sale”. Never had an issue. I’m a little cautious with the vehicles that call for 0w20.

"But Consumer Reports’ chief mechanic says there are some situations where synthetic oil’s resistance to breakdown can help prolong the life of an engine.

If you make lots of short trips, standard motor oil may never get warm enough to burn off moisture and impurities. That could hasten the breakdown of conventional oil. Also, if you live in a region with very cold winters or very hot summers, or if you use your vehicle for towing or hauling heavy material, synthetic oil won’t break down as quickly. While synthetic generally holds up better and can serve for more miles, it is important to not extend oil changes beyond the time interval recommended by the manufacturer—typically six months or a year.

Another good use for synthetic oil is as a salve for older engines prone to sludge buildup. This gunky residue can block oil passages and lead to a quick death of an engine. In the early 2000s, several engines from Chrysler, Toyota, and Volkswagen, among others, were especially prone to sludge buildup. This sludge forms when oil breaks down. Synthetic oil would be beneficial in those engines, as it is less likely to form troublesome sludge.

Using synthetic in these situations will prolong your oil life and require fewer changes. That’s a major benefit to the environment, as used motor oil is a major source of toxic waste in water. Your pocketbook will also thank you."

Eric Evart

"If you make lots of short trips, standard motor oil may never get warm enough to burn off moisture and impurities."
Sorry, but oil and water don’t mix. Lots of short trips have the same effect on synthetic as they do on dino. None on the oil itself.

The moisture that doesn’t get burned off is in the crankcase, and in the exhaust stream (which rots old non-stainless exhaust systems prematurely), as well as on components of the engine’s internal parts. Water vapor (H2O) is a normal byproduct of combustion. The hydrogen in the hydrocarbon (gasoline) bonds with oxygen atoms brought in via the induction system and form H2O, the carbon bonds with oxygen and forms CO and CO2. The moisture is normally carried out through the tailpipe, since the hotter exhaust gasses of a fully warmed engine can carry much higher moisture levels. Cooler gasses deposit their moisture on the cool surfaces they come in contact with. That promotes corrosion. It is the moisture from the combustion process that doesn’t get burned off, too much of it getting pushed to the crankcase by normal blowby.

Synthetic does not act as a salve. If an engine is sludged up, it needs to be desludged. Synthetic can, however, prevent sludging under extreme operating conditions (high heat). But we’ve already address that.

I cannot agree with these statements as quoted here. However, I would argue that if using synthetic helps you sleep better, it’s worth the added cost whether there’s any technical basis or not. If you prefer it, use it.

"Briefly, there are two types of “synthetic” oils on the market. Group IV oils consist of molecules that are synthesized from simpler chemical compounds. This lets the chemical engineers “tune” the characteristics of a lubricant to exact specifications. These oils flow more freely at extreme low temperatures and don’t break down at very high temperatures. As a side benefit, they generally can be specified one or two grades lighter than a mineral oil, which consumes less energy as friction inside the engine and saves fuel. These are superior products, and command a premium price. Mobil 1 is a good example of a high-end Group IV. Group III lubricants are made from reprocessed petroleum products normally left over after making crude oil into gasoline, diesel fuel, heating oil and other products. They’re more modestly priced, and have many of the desirable characteristics of the higher-priced spread."
Mike Allen senior editor at Popular Mechanics

"By the way, a lot of folks ask us about whether they should be using synthetic oil. Synthetics have a number of advantages over old-fashioned oil — most notably, they are less likely to breakdown when operating at high temperatures.
So, which should you use? Our advice is this: under most circumstances, we’d opt to use synthetic oil — in particular, if you have a high-end car, a high performance car, or if you happen to know that your model is prone to having the engine clog with varnish and other gunk. (Some Toyota V6 engines have been notorious for this problem.) In those cases, we’d recommend going the synthetic route.
If you’re already using traditional oil, and want to make the switch to synthetic, try using a blended oil which contains a mix of traditional and synthetic oils.
Synthetic oil remains a bit more expensive than regular oil. But, over the life of the car, the differential is probably not more than a few hundred bucks — and we think that’s worth it."
The Tappet Bros.

“RAY: So you certainly can go back to the synthetic blend next time. Or, you may want to stay with the full synthetic. It’s great stuff. It is more expensive. But because it lubricates so well and doesn’t break down as quickly as conventional oil, you don’t have to change your oil as often.
TOM:So that means we have fewer quarts of used oil to recycle or dispose of, fewer empty oil containers in our landfills and, not incidentally, less foreign oil we have to import.
RAY: And if you spend $40 on four quarts of synthetic and change it after 10,000 miles, or $20 on four quarts of a blend and change it every 5,000 miles, you end up spending the same amount – on the oil. But you save money on the filter and what you pay Pokey Lube for the labor. And you can skip the tailpipe polishing they inevitably sell you once they’ve got your car up on the lift.”

“Under dynamometer testing, Car Craft found in 2009 that Mobil 1 0W-30 generated an extra 10 to 15 extra horsepower over conventional 10W-20 and 20W-50 conventional oils… Much of that can be attributed to the overall lower viscosity of the tested synthetic, which results in less friction inside the engine than the higher viscosity conventionals. This is one of the advantages of synthetic oil—it can operate effectively at lower viscosities without breaking down…Your best bet for motor oil is a synthetic like Mobil 1, Valvoline SynPower, or Castrol Edge, which you can get for a moderate price if you hunt for sales and rebates.” Ed Grabianowski

“Finally, for those of you who drive your vehicle hard, tow a trailer, drive very short distances, sit idling and in stop & go traffic for long periods, live in a cold climate and/or if your car runs hot, quality synthetic motor oil, synthetic gear lube, and synthetic automatic transmission fluid is a wise investment that will provide the additional protection you require as well as last thousands of miles longer than conventional lubricants.” Don Stevens mechanical engineer, member of the Suncoast Region of the PCA and BMWCCA

What’s even more terrifying is found in this summary from https://www.hort.purdue.edu/newcrop/ncnu02/v5-029.html Get a load of this:

"Canola-based motor oils have rapidly evolved into a competitive product. In terms of pricing, they are highly competitive with synthetic motor oils. They are also the most “environmentally friendly” of the motor oils available maintaining properties of non-toxicity and biodegradability. In terms of functionality, they have exceeded expectations by surpassing both conventional and synthetic oils in the tests conducted. As a low friction fluid, these tests indicate vegetable motor oils, or bio-oils, are a competitive product in modern engine applications.

A pleasant surprise has been the response of engines in terms of tailpipe and manifold gas emissions. The reductions in nitrous oxides, carbon monoxide, non-methane hydrocarbons, and hydrocarbons provide an easy and effective way to reduce air pollution. The value of these exhaust emissions has now become established and, in effect, may have more value than the oil itself. The impact of conversion to a bio-based motor oil for each million automobiles driven 18,590,000,000 km per year (17,699 km per vehicle) would be staggering. Hydrocarbons from automotive exhaust would be reduced annually by 1,101 t; carbon monoxide would be reduced by 87,475 t; and nitrous oxides would be reduced by 1,416 t."

better butter

How would it decrease nitrous oxide ,if the combustion chamber stayed the same temperature ?

You got 165K miles using the type of oil designed for your engine.

Switching to synthetic will only cost you more money.

It will do nothing to extend the life of your engine in any noticeable way.

If you change your oil every 3-5k miles, dino is fine. As stated, Toyota V6’s used to sludge. I have always used synthetic in my 99 V6 Camry, because it was a one of those with the sludge problem. New Toyotas all call for 0W-20. That only comes in synthetic. They also increased the mileage between oil changes to 10k miles. Standard oil could not handle that.

RE: Toyota sludge

I had a '99 Toyota with a sludge-prone engine. As a solution/workaround for that problem, Toyota dropped the recommended oil change interval from 7500 miles down to 5000 miles using dyno (non-synthetic) oil.

Using dyno oil and changing it every 5000 miles worked fine me for me. I got rid of the car at 200K miles because rust had taken over.

Fortunately, Toyota fixed their engine design problem (that provoked the sludge) by the 2003 model year.

I do agree with knfenimore. If you have a problematic engine that is prone to sludging, then using synthetic is more insurance against the sludging occurring.

Synthetic oils are less viscous than mineral oils. Because of this, they lubricate earlier after startup and there is less engine wear each time there is a startup. That could be why synthetics perform better when the car is driven short distances frequently.

@jtsanders Yes, synthetic oils have a higher VISCOSITY INDEX! That means that the viscosity changes LESS with temperature changes. At 0F, a synthetic flows better than a dino, and at very high operating temperatures (like trailer towing) it thins out less. However, a 30 weight dino and a 30 weight synthetic have the same viscosity at normal room temperature!

It’s s little like comparing cooking oil with lard or butter, both of which change viscosity dramatically compared to cooking oil.