To use synthetic motor oil or not?

[Oz]

The message search shows there's a lot of good info on synthetic oils contained in other posts across the forum but, there's isn't one solely dedicated to the question:  "To use synthetic motor oil or not?"

This should be a good place collect input, info, and feedback about it in one topic.  Like politics or installing headers, this is a highly debatable topic.  Remember, everyone has their own opinion based on their knowledge, experience, and research so please, all info is welcomed, just keep it impersonal - simply stating your point of view so all readers can make their own, educated choice.

   

P.S.  For a quick summary of the results, I've added a poll.  If you provide feedback, please remember to place your vote!  If you don't post a reason for your preference, don't place a vote as unsupported votes don't help.

[ClydesdaleKevin]

Personally I recommend a good regular oil, NOT synthetic...big old waste of money if you ask me.  If you change your oil every 3000 miles like you are supposed to (and don't believe the synthetic oil companies, you should STILL change your oil every 3000 miles even with synthetic), you are better off with a good old regular oil, like Castrol, Pennzoil, Quaker State, etc.  If you drive as often as we do, you can even use the Walmart brand, since it doesn't sit for a whole year like in most casual RVer's rigs...if its going to sit all winter then go with Castrol, etc.

[vincewarde]

I have been running synthetic in all my vehicles, with the best filters I could find, and changing once a year, since the early 1980s.  The only exceptions have been a few vehicles that came to me with high oil consumption.  Those got the standard oil, change every 3,000 miles, treatment.  I run all my cars until they won't go anymore - unless they die in an accident.  I have never had a single oil related failure.  Not one.  When I lost a head gasket in my Nissan P/U at 190k due to a colling system failure, I got to see the inside of a motor with over 130k of synthetic changed once a year.  I was very impressed.

My wife drives a 2000 Kia Spehia, current mileage, about 190,000.  Zero oil consumption.  Engine still running strong and gets the same mileage as it did 150k ago when we bought it.  My vehicle for the last 12 years has been a 1993 Explorer 4x4 with a 4.0L V6.  Just turned over 220k.  Doesn't burn a drop of oil.  Engine still runs strong too.

So, to each his own - but that's been my experience with synthetic oil.

[PwrWgnWalt]

I'll add my opinion, too...

In short: synthetic oil can be a viable option - but ONLY after the engine is broken-in after a "rebuild" (meaning: cylinder bores honed, new lifters, etc... not just a new water pump). Opinions on this vary, but I like at least 200 miles of varying load (e.g., not highway driving on cruise control). Bottom line - always use a quality oil and filter, and change your oil every 3000 miles after the break-in (first) oil change.

Me, I always break-in a new (rebuilt) engine with straight 30 weight (HD30) petroleum oil - AND use an additive (zinc & phosphorous "ZDDP"; or, "Break-In" additives).  You can also buy special break-in oils that have this stuff in them.  BTW - the zinc/ZDDP additive is an excellent choice to add for these old engines at every oil & filter change. Read on for more info "why".

Our old-technology engines need to have some metal "wear" to properly get everything settled in right and mated to other contacting pieces. Synthetics are so good at being 'slippery', they don't allow this to happen during break-in.  But once broken-in, we want that wear to stop (or slow way, way down). Oils used to have a good amount of zinc & phosphorous in them - this simply helps the engine protect itself from too much metal-on-metal contact, in various ways (especially piston rings and camshaft lobes). Nowadays, the zinc and phosphorous are all but gone from engine oils (you have to buy special oils to get them).

My old Dodge 360 c.i. engine in my 1971 W200 (Power Wagon) was rebuilt (by me) in 1991 and is still going strong today with over 112,000 miles on it. It runs 3200 rpm on the highway at 65 mph and was broken-in using the above procedure.

And although piston aircraft engines are different, they operate on the same 4-stroke combustion principles. Break-in for aviation engines is to run "Straight Mineral Oil" until the first change - it allows things to seat together well. We've been running a semi-synthetic in our back-then-newly-rebuilt airplane engine for over 15 years - and it has done very, very well (according to the A&P mechanics who have inspected it, annually). 

Synthetic, Semi-Synthetic, or petroleum oils can be the right choice - I run semi-synthetic in the plane, but regular Castrol petro-oil in my auto engines (with zinc/phosphorous additive). The 440-3 in the MH will be fed regular (or high mileage) petroleum-based Castrol 10W-30 (or 10W-40, esp in summer) with ZDDP additive.  Might even consider the semi-synthetic blend, but always staying with Castrol.  (One should not mix oil brands due to the differences in detergents, etc... used to be a 'given', may not be as critical today, but I still stay with one brand)

[MotorPro]

Once the engine is broke in it is fine to switch to synthetic. It works as well (but no better) than regular oil.

I have been in the engine rebuild business fo 25 years . In that time we had 2 engines go bad. Both lost cams after the owner broke the engines in with synthetic dispite my telling them not to.

[LJ-TJ]

Boy do I expect to get spanked on this one. What is the purpose of motor oil?
1) to lubricate.
2) Cool the engine.
3) To flush contaminates which hopefully will be picked up in the filter.

For me personally, I use Rotella-T 10W-40 synthetic. As a rule of thumb I change oil and filter every 2,000 miles or in the spring when we start a new season. There's an old saying you can pay me now (change the oil frequently) or pay me later ( replace the engine). It's just cheep insurance. But that's me.

[Oz]

Is that synthetic or regular, TJ?  That's what we're looking for here.  What members are using and why one or the other.

Let the spanking begin!

[Oz]

Not an engine tech, just an end user.  I haven't kept any vehicle for more than 100,000 miles and most, I put less than 75,000 miles on.

In my RVs and cars, I've used regular motor oil, even the Wal-Mart brand.  I changed oil every 5,000 miles on my cars and every 3,000 on my RVs. 

From a novice, user point of view, I looked for the following things:

Is the oil really black?  I saw that the oil was dark brown so, I could reasonably assume it hadn't been worn-out yet.

Did it smell burnt?  - No.  Okay again.

Holding the dipstick up in the light and checking the bottom of the oil pan for unusual metal deposits.  Okay again.

So, I surmised that using standard oil was fine and that spending a few times more for synthetic wouldn't provide any additional benefit.

[Froggy1936]

Actually science has surpassed mother nature synthetics are a better lubricant than oil In fact it is so slippery that new rings will not seat if synthetic is used from the get go (new camshafts need the phosphates for break in, special additive) I dont know if phosphates are compatable with synthetics.

Regular multigrade oil suitable for prevailing temps will do just fine in R/Vs But if you are going to be turning 8000+ RPMs synthetics are better ! As far as changing i go by color of oil on dipstick or once a year.  Mileage is immaterial except in cases of contamination (water/fuel) & i always use STP to top off level, I never let the engine fire till it shows oil pressure on the gauge (except hot starts)  Thats my 2cents worth When i replaced the rod and main bearings on my Chev 350 @ 85,000 mi the old parts looked like they just came out of the box  Frank

[bluebird]

I use both. I use regular oil in the MH because I don't put many miles on it and change it yearly. I use synthetic in my race cars and my corvette. I bought my vette a couple years ago, high milage car, 126,000. It had leaky valve covers, when I pulled them to replace the gaskets I couldn't believe how clean this engine was. It now has 146,000 and doesn't use any oil between 5000 mile changes. I also use mobile 1 and Lucas oil stabilizer in my race car engine. I used to change oil after 30 passes and still had to replace the bearings yearly when I used dino oil. Now I run all year on an oil change, and the bearings are 3 years old. I do run E85 for fuel so it is cleaner than regular gas so that does make a big difference on contaminates. Synthetic is far superior, my 02. The bearing and rod bolts are so slippery, in my race engines, it's hard to hold onto the parts when doing winter maintenance.

[tiinytina]

I bought my Tacoma (4cyl 4x4) new in 1998, have used nothing but Mobile 1 every 5k miles, and she just turned 361,000 this week and runs like a top. There is ZERO gunk inside the oil fill port and the dipstick looks new.  My first Toyota truck I switched to Mobile one after 125K on her and blew my front oil seal and or it had been blown and the synthetic cleaned out the gunk that was clogging it closed.. LOL).

Now.. bought a 2003 Lexus RX SUV in 2006 with 36,000 on it.  This vehicle had been serviced by a lexus dealership its entire life.... both the dipstick and oil fill port were caked with black residue.  I've been running Mobile 1 in it since and just turned 117,000 on it.  She runs great.

Husband has a 2003 Saturn ION3 bought in 2005 with 24K on it... Mobile 1 every about 5k (not my job LOL) and it has 280K on it now no issues with engine (though who ever engineered the suspension system needs their head examined... it eats front struts every 80K which are getting harder to find since Saturn went out of biz and last round cost $600 in parts)...

Now the RV.. being 67K when we bought it, and now 25yrs old.. I use the high mileage oil, changed every spring regardless of mileage.   I may try a half synthetic on her but I wouldn't go all synthetic at this point... new engine yes.. old work horse you don't want to change feed on... ie ain't broke don't fix it.. LOL

Tina

[Oz]

Okay... let's back up a step... I'm seeing that a people are showing a preference for synthetics for use in CARS and such with higher RPM and performance engines, yet even in the same post, regular oil in the RV (?)

As much as it is appreciated and a benefit to have all the aweseome, additional info and feedback on POV preferences, what we're looking at primarily is for MOTORHOME use so please, if you don't use synthetic or "dino" oil in both, place your emphasis on RV application so it's easier for us moto-dummies to pick out.  (notice that I've gone back and did this in the previous posts) Thanks!

[chicknnhead]

I don't turn wrenches for a living, but i do have some talents in that area. I tried switching to Synthetic once. it seemed to be to thin of an oil for this old porous metal. i undertand in the new RV's with the newer engine that may have not such of a porous metal like they did 30/40 years ago....ie almumnim heads blocks etc it would be fine. IMHO i think conventional in these older RV is fine

I went back to conventional oil, and i change once a year considering the RV only gets 1500 miles a year on her.

good thread so far with some good reading

[bluebird]

If I used my MH over the road or ran more than a couple thousand miles a year, I'd switch it over to mobile 1 in a heart beat. I put on less than 800 miles last year. I change my oil every year or 3000 miles now. I'm retiring next Jan. and will switch my MH on the next change. I'm dumping good oil now and the mobile 1 cost 3 times more. I have too many vehicles and don't drive any of them enough except the Vette. I'm sold on Mobile 1 and Lucas stabilizer which I use in all my vehicles, except the wifes G6. We have it serviced at the dealer as it's still under warrentee.