Diesel oil on a gasoline engine?

[ecogabriel]

Hello to all,

When I got my 1986 LX-i, it was pissing oil out of every single shaft seal you may think of (leaking is an understatement). So the guy that had it poured a quart every hundred miles or so. The oil was therefore quite clean as it never stayed long enough to get dirty so in the first few miles I did not bother with replacing the oil. I had first to stop the bleeding; EVERY single shaft seal including distributor and rear crankshaft seal was replaced (PITA).

When deciding what oil to use I noticed that oil for diesel engines is generally suitable for use on gasoline engines. They include the API classification for diesel engines (eg. CJ) and gasoline engines (eg. SM).
A little extra research revealed that that newer API classifications for gasoline engines have lowered phosphorous content than earlier ones. One reason is that phosphor "pollutes" catalytic converters reducing their efficiency over time. On the upside, high levels of phosphor increases protection against wear in places like camshafts and valve trains. Because the engine on the old Accord was designed when phosphorous content in oils were higher, I though that the engine would benefit a little from the extra phosphorous content; as for the effect on the cat converter (we have emissions here in Atlanta) that was also discounted when the car was designed. Besides, the car is already 22 years old so a new cat may be needed at some point in time.
There was an extra consideration: cleaning additives. That would make no damage on an engine that is already clean. If anything, it will keep it clean for longer.

So, for this car I went with a diesel/gasoline engine oil (Rotella T 15w40). I would have liked a slightly lower viscosity (like a 10w40) but for the weather here 15w is fine and the car starts without problems. Besides, 15w40 fits what the car manual says regarding viscosity as it contemplates using even 20w50.
For colder climates, there is an option of a full-synthetic oil (Rotella T 5w40). Prices for either type are good, being somewhat lower than similar "gasoline-only" oils.

Before going "diesel" on oils I did some homework. I remembered from long ago (when living overseas) that many gasoline engines were also rated for use on diesel engines (part of the story that moved me to do the research in the first place)
Shell has a bunch of information on this particular topic. You may even notice that those diesel oils are being used by... motorcycles!!!
I have included one link below for reference; there i a forum in which people ask questions and get answers from others and forum moderators (that are Shell engineers). You can even send your own question for a more specific answer
http://www.shell.com/home/PlainPageServlet?FC=/rotella-en/html/iwgen/ask_our_expert/app_askourexpert.html
http://www.shellusserver.com/products/pdf/RotellaT(CJ-4).pdf
http://www.sopus-staging.com/staging/ShellRotellaTSynthetic_TDS_v10.pdf

THIS IS NOT A RECOMMENDATION NOR A SUGGESTION FOR ANYONE TO DO ANYTHING OF WHAT I DID.
I am sharing what I have found; for some this information may be useful.

Happy New Year for everyone!!!

[nfs480]

The only mention of using 20w50 in the owner's manual is for manual transmissions, not the engine itself. You should use either 5w-30 or 10w-30 in the engine. I use 5w-30 myself. I work at a Valvoline Instant Oil Change and from what i've seen I would not use Diesel oil in my car over any other type of oil, especially one as heavy as 15w-40.

[evil88accordLX]

my car leaks "some" oil also, and in times of emergency ive even used whatever was available, including heavy duty lawnmower oil. i think the A20 has a lot to do with being able to withstand non-correct oils. i sure wouldnt do it to a B or K-series engine.

[nfs480]

Well, in an emergency any lubrication is better than no lubrication, and the A20 is one tough engine, but if possible i'd use either 5W-30 or 10W-30 (I use 5W-30 since it's -11 here, lol) which is why I carry an extra quart of 5w-30 Valvoline MaxLife Full Synthetic in my trunk in case of emergency.

[Oldblueaccord]

with 15w40 I would only worry about cold weather start ups on Honda's. If its not cold by you or your car ins in a garage I wouldn't worry about it to much.

I think your more interested researching the zinc that were in oils and are not now. Its a concern with older domestic V-8 with hydraulic lifters,large cams and heavy valve spring pressures. I plan on running it in my Chrysler on break in in the very least and hope dont wipe a cam lobe.


wp

[ecogabriel]

The manual in my 1986 Honda specifies several different oils with 10w40 and 20w50 covering ranges from about 20F all the way up to 100 or above, and that was for the engine itself. I cannot recall my manual from memory but i saw three or four different "bars" with the different oil weights from 5w30, 10w30, 10w40/20w50.
But I also saw in the 1989 service manual available in this site that they recommend a lighter oil weight (10w30 if I remember well) and they showed the 5w30 for very cold climates. For the sake of it I will try scanning the page from my owner's manual and uploading it here.

My main concern with researching this issue was phosphorous content in oil. By the time the A20s were designed and produced the oil available had more phosphorous content than what is present nowadays. Additional phosphorous protects parts under heavier load (e.g. valve lifter, camshaft lobes, and crankshaft journals). Diesel oils need a heavier package of additives and cleaners because of the harder conditions under which diesel engines work. When the oil is suitable for gasoline engines there may be an extra benefit in the form of an increased level of additives.
I agree that for those in cold climates the 15w40 would not work; starting would be quite difficult if not impossible with a weak battery/starter. There is a 10w30 in production of the same oil that might work but I cannot make an statement about it because I do not have such a cold here. Perhaps the 5w40 (synthetic) would be the best choice; besides being full synthetic oil it has the additional additives as in earlier Sx specifications (plus I get stronger cleaner additives)

Incidentally, I remember from my overseas stay that engine oils were formulated for both gasoline and diesel engines which was the case in South America's southern cone in the mid-1990s). I would like to hear how is like in other places too.

I posted this because I thought some would find this info useful; getting an oil that does the job with an extra seems worth for me.
Anyways, I will get the oil analyzed once I change it. For $22.50 I will know engine wear; ten bucks more buys knowing how long the oil can be kept in the crankcase beyond what is recommended. Knowing this makes little sense when you have one car or two, but fleet operators save bug $$$ with those analysis. Oil changes cost quite a bit in large diesel engines and throwing away good oil is burning money without any return. For me, knowing how well the engine is holding after 130k makes sense.

[Hauntd ca3]

if the oil has a rating of prob sf or better, its fine to run.
i run castrol magnatech which has the sm rating and also cf or better rating.
have put that in diesils and they run sweet on it.
the thing with oil aimed at diesels is that they have more detergent in them to deal with the higher level of carbon in the blow by in diesels.
if its speced for both si and ci engines, it will be fine imo

[Krisverde]

I use rotella T 15w40 in a b230ft...but thats a Volvo engine and I have no problems using that oil either.

[cubert]

When I had my 3g, it leaked roughly a quart of oil a day. Thankfully I worked at a motorcycle shop, which had plenty of spare half empty bottles of oil laying around. That car saw everything from 5w-20 to 20w-50, and never skipped a beat. Starting was never an issue, but then again, the oil never stayed in for very long :kekeke:

[russiankid]

I run Chevron Delo 15w40 in the summer in my BMW. It is a diesel oil but its fine for gasoline engines. The oil does not break down as fast as regular oil and its much cheaper.

[lostforawhile]

I wouldn't worry too much about the modern oils, they are far supirior to anything out when the car was produced. I mean the hot rod guys run modern oil in car engine from the 40's and 50's. If you worry about anything worry about the dam alchcaol in the gas.

[russiankid]

I wouldn't worry too much about the modern oils, they are far supirior to anything out when the car was produced. I mean the hot rod guys run modern oil in car engine from the 40's and 50's. If you worry about anything worry about the dam alchcaol in the gas.

I worry about my BMW because its a high output motor, and in the summer the engine bay is very hot.

[lostforawhile]

I worry about my BMW because its a high output motor, and in the summer the engine bay is very hot.right,but modern oils are designed for that type of operating enviorment. engines are a lot tougher on oils then they used to be. use what BMW has reccomended,they spent a lot of time and money figuring out what works best,

[ecogabriel]

I agree that modern oils are far superior than whatever it was used in the earlier days. But is is also true that (at least in the U.S.) oils for gasoline engines (I think from SG onwards) have lower phosphorous level than before. For engines designed and built after the reductions have taken place there is no problem. For those engines designed and built BEFORE the question is how much tolerance the engineers/builders built in engines themselves to run in conditions that were less than the ones they predicted.
In any event, I am pretty sure that there is no problem with lower levels of certain additives in newer oils.

The fact is that diesel engines work under more severe conditions than gasoline engines (higher temperature, higher compression rates, higher loads on bearings, valves, and shafts,). Therefore, using an oil that has an additives package to withstand all that harshness in a less stressful environment would give an additional margin of protection at no additional cost.
If I can get away with using one of those I will take the one with higher additives even if they are not necessary; as long as they do not hurt (that would be the case in a very dirty engine in which stronger detergents may dislodge some of the old crap) I will go the higher route. I had seen the engine from the top and it was quite clean so I figured that it would not hurt using it.

From some postings here it seems that the difference between diesel oils and gasoline oils is more of an U.S. issue, dictated (probably) by fuel-efficiency and emissions concerns.
I remember my South American years in which any oil I used was suitable for both gas and diesel engines; I tried Elf, Agip, Shell,and Castrol oils back then and all of them were classified as API S* (gas) and C* (diesel). In addition, many cars run dual fuels -gasoline and compressed natural gas- and they used the same oils as the others. It seems to me that the picture is the same in other places as well (at least in NZ).

Bottom line: diesel engine oils have higher level of oil additives. Using them in gasoline engines (as long as they are classified as S*) may give additional protection at a similar or lower value than gasoline-only oils.
Whether the engine actually benefits from the additional protection in the oil is more subjective and it would depend on specific user conditions.

The exchange has been quite interesting. Thanks guys!

[OldSkoolA20accord]

i used butter as oil in my go cart once. worked great.

[ecogabriel]

Attached is the page of the Owner's manual talking specifically about engine oil densities. See the chart at the bottom of the image for the temperature/viscosity chart
For this model (1986) it seems that 10w40 covers the widest range from about 0F; lower density oils are only recommended for very low temperatures.
Check your owner's manual for the correct viscosity. The 1989 US service manual listed here has a different chart for engine oil viscosities. Perhaps it also applies for older A20 engines too...

[ecogabriel]

:wtf:
How do you upload a image to the forum? If anyone can help me (I'm such an ignorant) I'll appreciate it!
:cheers:

[w261w261]

When I had my 3g, it leaked roughly a quart of oil a day. Thankfully I worked at a motorcycle shop, which had plenty of spare half empty bottles of oil laying around. That car saw everything from 5w-20 to 20w-50, and never skipped a beat. Starting was never an issue, but then again, the oil never stayed in for very long :kekeke:

Ahhhh, you worked in a bike shop and you had a car that was dumping a quart a day onto the road? Did you also ride a bike?