This appears to be a basic question but I could not find a straightforward answer in the archives...

I have decided to go with Mobil 1 synthetic oil for my next oil change. I recently (4.5 miles ago!) replaced the camshaft and had a machine shop redo my head (with valve seats for unleaded). I believe the bottom end of the engine has about 120k miles on it. I'll put a few miles on the car when the weather warms up and I get a brake issue sorted out, then I'll change the oil and filter.

I thought that there was only one viscosity for the Mobil 1 (I'm using 0-30 W in my new car) but I noticed that Costco sells a 5-30 as well as a 10-30 and then the Mobil 1 website mentions a 'European car' formulation. What is the best formulation to use for my car (stock 1967 B-18 with details as above)?

Also, I plan to go with the Mobil 1 or equiv synthetic for gear box (M-40) and differential. What do I need for these applications?

Any suggestions sincerely appreciated.

Many thanks,
Kai
(1967 Duett)

Mobil 1 (and I presume most synthetics) have a Diesel-use API service rating shared by Chevron Delo and other lube oils intended for turbo diesel engines. The significance of this is superior anti-wear and anti-corrosion properties, according to a Car & Driver column by Patrick Bedard a few years ago. A consultant in lube oil additive package design was Bedard's source. The focus of that article was lube oils for old cars that are not in daily use, and which collect moisture and acids, and get started with dried-out wear surfaces.

It was claimed that lube oils marketed for catalyst-equipped cars are being given less of those addditives, to cater to catalyst health, and that we should avoid oils that are not rated for diesel engine use, ie, that have only two-letter API designations beginning with "S." Diesel-use designations begin with "C", such as CH.

Considering the known cam and lifter wear problems in B18 and B20 engines, it seems advisable to use lube oil with the best wear and corrosion resistance, and in a thin enough viscosity that it readily wets those parts by splash and mist.

Synthetics that I have used all seem to seep past gaskets and seals more readily than natural oils. I use Mobil 1 now in a DOHC catalyst car 14 years old (mixing 10-30 with 20-50) and Delo 15-40 in a 38-year-old, un-overhauled, pushrod-engined car that has cam and lifter wear discovered 25 years ago during a valve job.

C.O.Greenlaw, Sacramento Cal.

I don't think these cars really need mobil 1 under normal driving
conditions. Mobil 1 is great stuff but I think most of the time you
want to use it in super high heat situations like if you have a turbo
or because you want to use the same oil in the motor for 6 months /
10,000 miles between changing the oil. B20s under normal driving
conditions should never get into temperature ranges where a normal,
high quality oil would break down. Also, even with D-Jet fuel
injection, a B20 will get enough gasoline into the oil that you
wouldn't want to leave it in the crankcase for 6 months and you would
never ever dare do such a thing with carbs because you'd be driving
on 10% gasoline / gasoline residue in 6 months.

I used mobile 1 15/50 in a 164 because I live where it gets to be
130 degrees or more at street level and the temperature gauge would
sit in the middle of the range most of the time, higher at times and
dive into the red when the motor was shut off. I replaced the
radiator and put in a 160 degree tstat and that solved that problem.

In a B20/B18 motor I would stick with a good diesel motor oil like
chevron Delo 600 15/40 and change it every couple months / 3-5k miles.
That is, unless you have a turbo or supercharger or unless you spend
long periods of time (2-10 minutes) at continuous full throttle, ie
unless you tow things up long hills or race.

Oh, and your motor will last far longer if you use good oil filters
like the mobil-1 filters or the Mann filters volvo uses OEM.
chris

I disagree. Full synthetic motor oil is good stuff and there is no reason to not use it. Your rig doesn't have a cooler so that poor oil sits in there getting hotter and hotter and only cools by contact with the sump.

Changing high quality filters on a routine basis is very important, yes.

If you get 10% fuel in your oil then you have a major induction adjustment issue or destroyed rings. No engine should have contamination that bad.

I'd use the "10W30" spec and be happy.

Insofar as the tranny is concerned, it is not picky. I happen to use redline GL-5 spec in my M40. The M41 reputably cannot use synthetic due to the cone clutch in the OD but I'm still on the fence. gonna try it unless someone else can irrefutably show me it caused trouble.

--
Mike!

I agree that modern synthetic motor oil is fantastic stuff. It
is also really expensive. It also turns out that modern quality
dyno motor oil is also really damned good stuff too, and is lots
less expensive. If I had money to burn, I'd run mobil 1 in my
car, no doubt.

That said, Delo 400 15-40 is really really good oil too. It
is about a quarter the cost.

Synthetic oil doesn't coke up in high heats like in a turbo.
If your B20 has any spots as hot as a turbo, it's in terrible
shape. Synthetic oil will last 3-5 times longer in a motor
before it needs to be changed but in most B20s the oil will get
contaminated with stuff far faster than the oil would wear out.

Personally, if I had money to burn, I'd spend it on higher
octane fuel and advance the timing a little bit; that's an
advantage I'd actually notice vs the advantages synthetic
offers over a quality normal oil.

On my VW TDI, however, I *only* use delvac (mobil 1 5-40)
fully synthetic.
chris

A real-world study is being performed (can't find the link right now) on full synthetic motor oils over an entire year's duration (approx 10k miles) by a reputable group of amatuers (meaning not automotive engineers) by taking samples for a lab to check for wear and contamination products (and oil parameters) every 1k miles.

Results are only in for Mobil 1 and AmsOil as yet but both are encouraging to the ones who want to believe that extended intervals are OK. Both oils passed the one-year mark just fine.

I was convinced before and am fully sold now (I happen to like Syntec myself).

Add by-pass micro-filtration (they aren't) and the sky's the limit!

Insofar as combustion by-products are concerned, if the oil gets fully warmed up and the crankcase breather system is functional, loading of the oil takes a long time indeed. Swift contamination of the oil means a re-ring is necessary at a minimum.

No, I'd not waste full synthetic on an old tired engine that was close to rebuild time, either.


--
Mike!

Update: found the site http://neptune.spacebears.com/cars/stories/oil-life.html

Turns out the Mobil 1 was for 18k miles and the amsoil for 14k and they want to do the mobil 1 again (pity, I'd rather see a different oil as the mobil 1 did fine).
Yea, its a chebbie 350 but that's just twice as many cylinders to blow-by!

Mike,
FWIW, I have Mobil 1 75W-90 in both my M41s -- one of them going on 4 years now -- and have had no problems, except that the stuff seems to weep past the bottom plate gasket more than standard gear lube. It's such a small amount, however, that it doesn't bother me -- no puddles on the floor, just the ocassional drop. BTW, before starting to use it I checked with Duane Hoberg. He gave it his blessing, and I stopped worrying.
Bob S.

I'm running Mobil 1 in my M41 as well. Two years and no problems so far.

I'm constantly amazed at the amount and variety of opinions that are expressed whenever oils and lubrication are brought up. I used Mobile 1 in my Ford Crown Vic Police Interceptor (which I sold to buy my PV544) mostly because of the high operating temps and the high speed driving that car was subject to.

As an added bonus, I also picked up 3mpg using Mobile 1. All around, a win-win situation!

My 544 has a B20 and automatic with over 100,000 miles since overhaul. In 6,000 miles of driving, it burned or leaked 1 quart of oil. Normally I'd have changed oil at 3,000 miles, but frankly I just got too busy with my Dad's health issues to take the time. Even so, at 6,000 miles the old oil was still clear, looking pretty much like it just came out of the bottle.

Having removed the rocker cover to adjust the valves, the inside of the engine appears to be especially clean, also. According to the hundreds of receipts that came with the car, the previous owner was a fanatic about maintenance up until a few months before she sold me the car.

Our weather out here in the desert doesn't call for low-viscoity oil, so I put in 10-30 Valvoline, which is a little thicker than the 5-20 the previous owner used. Depending on the season, I may go to 10-40 for summer, since it gets into the 120's fairly frequently, and I like to drive through Death Valley on my way to Las Vegas. :-)

I don't see much indication that the engine is burning oil; the tailpipe residue is medium-gray, and there's no smoke on cold startup. The engine does leak a few drops when parked, and I haven't found the source of that yet.

When I've had time to give the engine a thorough going-over, checking the valve height, etc. and I'm sure it doesn' need tearing down in the near future, I'll be changing over to Mobile 1 with the sure knowledge that it will serve me better, and cost less in the long run, that fossil oils.

Just my 2 cents worth!