Iv'e been using Rotella 15w40 in my 73 F100 for a year now. Engine seems to be ok, its original with 56,000 miles on it.

Now I hear people telling me "that 15w40 Rotella is going to kill your engine get it out of there" Others say "the 15w40 is ok to use but still doesnt have everything your engine needs".

So now on to the question. Do I stick with the 15w40 Rotella and add ZDDP to it or do I go back to a 10w30 or 10w40 oil and add ZDDP to it?

 

well i just use 5w30 not sure why you'd be using 15w40

 

Rotella CJ4 15W40 and 10W30 each have over 1300 PPM Zinc. More than enough for a street motor.

Which is also 100 PPM MORE than the all too glorified Valvoline VR-1 Racing oil.

I run Rotella in my truck and my motorcycle.

Josh

 

15w40 is the only Rotella Oil I can find in my area. I didn't even know they made other weights of Rotella oil until somebody told me.

 

I've used 5w 30 Mobile One for years with no issues. In my cars I use Castrol Syntec. I dont have reasons why except, Ive never blown an engine and I am hard on vehicles.

 

You can run pretty much any oil in a engine with a flat tappet cam with that many miles on it. It won't hurt the cam or anything else.

 

so will someone inform me whats so good about 15w40 rather than 5w30 thanks

 

Depends on location I suppose. Here in WV temps are usually mild in the winter but sub zero is never a shocker. I keep hearing "if it aint broke" you know the rest lol. I am notoriously hard on vehicles but Ive never toasted an engine so to get me to change oils and filters would be a very tough sell.

 

I guess I will keep using 15w40 Rotella T unless a store close to me starts having 10w30 Rotella T. Engine runs good and quiet and starts right up in the winter. Been runnin over a year with this oil and no problems.

Can't be no worse than when I first brung the truck home. I found out the oil hadnt been changed since 1987.

My other three trucks are well past the brake in stage but im running 10w40 Havoline in them. Should I add additive to them?

 

The quality of oils have advanced so much that, the 3000 mile rule is obselete. The last car I bought was a brand new Hyundia Tuscon, great vehicle btw...and you could change the oil with crisco if you so desired, as long as it was within 4500 miles to keep it under warranty.

 

This is a wide open subject with lots of exceptions, but in general the higher the viscosity the thicker the film that separates the wear surfaces. The exception is in tight tolerances and cold temperatures where a thicker film cannot properly flow.

The big push for 5w30 in the auto industry was led by improved fuel economy, tighter tolerances and improved oil performance. My opinion, for what its worth, most engines in our trucks will thrive with 15w40 except in the far north during winter.

Like Bullit390 said,Oil has changed in the last few years and our engines need zinc to protect the cam. You have a few choices, the higher priced synthetics (Mobil 1, Royal Purple, Redline etc.) the diesel oils or add a bottle of ZDDP.

I learned the hard way, I ruined two cams before an engine builder showed me cams run with different oils.

 

So I guess now the question is with an engine that is 37 years old but only has 56,000 miles on it should I continue using the 15w40 Rotella im using now or should I give the 10w30 Rotella a try?

The only problem I have seemed to have so far with the 15w40 is sometimes it will get down to around 15 degrees for a little while around here in the winter and I will have valve/lifter chatter at start up a few seconds. When it gets to around 20 degrees and up I don't have that problem.

My fear is the 15w40 is doing damage even though I cant see it or hear it. But in the long term the damage might start showing up.

 

I used to run 20w50 in my 390 and 360, and in the winter, they were hard to start, and sometimes rattle a bit in the top end. When I took them apart, they had NO wear after years of beating on them.

I later started using 10W40 in the last 390 I had, in the winter months, and it definitely helped.

15w40 is a good middle of the road. If it's cold enough that it's causing valve train noise, go down to 10w30.

But I don't think you're doing any "damage" to it

 

There is no substitute for synthetic oil - it is simply the best way to protect any engine, period.

The protective oil film provided by sythetic oils is harder and there is no "geological history" as with crude based oils. Unlike crude based oil, the molecules in synthetic oils are all exactly the same size (albeit smaller molecules than those of crude based oil - and that can lead to seepage in some engines with weak gaskets but it is rare and easily remedied).

Ideally, we want an oil that is thin when it is cold so that it circulates as quickly as possible through all galleries to surfaces which need lubrication and prevents metal to metal contact during cold starts. However, we also want oil which stays thick when it is hot rather than breaking down and thinning out to the consitency of water, as is the case with most crude based oils.

Studies have shown that the best protection for engines at regular operating temperatures and highway speeds is provided by 50 weight oil, but the problem is that straight 50 weight may be fine for racing engines (which are built to loose tolerances, warm up quickly and are usually manually presurrised at the oil pump prior to firing) but will cause premature wear in street cars due to the slow circulation when cold and thick, leaving parts exposed for too long during the starting/warm up process (it has been shown that an improper cold start can cause as much wear as hundreds of miles of driving).

The first number in a mutli viscosity/muti grade oil represents the viscosity (thickness) of the oil when it is cold (the lower the number, the thinner the oil when it is cold). The second number indicates the thickness/viscosity of the oil when it is hot (the higher the number the thicker the oil when it is hot).

The thinnest/lightest crude based oil available is a 5W20 or 5W30 - synthetics actually offer a 0W30 (ideal for those living in very cold climates, but not the best protection at high operating temps or in summer). The thickest crude based oils are 15W40 or 20W50 (note how high the initial numbers are - that's too thick for cold starts!!).

Only synthetics can offer the best overall solution - in the form of 5W50 viscosity (thin when cold, thick when hot - can't beat it!). Multivisosity/multigrade crude based oils cannot make that stretch (the additive which creates/allows multiviscosity in crude based oils will begin to break down when the thinnest/thickest points are stretched too far apart) and that's why you don't see 5W50 crude based products - only synthetic.

With the exception of newly rebuilt engines (which should usually be run for c.10K miles to allow surfaces to mate well before using synthetics) there is no engine which would not benefit from the use of 5W50 synthetic oil - especially the hard working engines in our '60's/'70's/'80's trucks.

I have been assured by a (Rolls Royce trained) mechanic that even very modern, low emission engines which are built to very tight tolerances and clearances which are intended to reduce emissions (i. e. blow by, etc.) and which call for light oils (0W20, 5W20, etc.) will run fine on 5W50 but those are judgement calls to be made by the owner of the vehicle (with some input from the manufacturer's service techs).

There are also other benefits to synthetics - they trap contaminents and keep them in suspension, which are then flushed out of the engine during the oil change, leading to a cleaner and cleaner engine. In the case of crude based oils, the contaminents are released from the oil when it cools and they form sludge and deposits in the crevesis of the heads, oil pan, etc. over time.

Obviously, the initial cost of synthetics is higher than crude based oils but the actual long term cost is about the same because synthetics do not need to be changed as often as crude based oils. I still believe that crude based oils should be removed from an engine after c.3,00 miles or 3-4 months because they will have lost much of their protective elements, and acids will begin to accumulate (which will eat bearings).
On the other hand, synthetics can be left for 10,000 miles without worries (our daily driver BMW and Mercedes came with synthetic oil from the factory and require oil changes only once per year according to the service schedule). I know that some guys have trouble coming to terms with leaving oil in an engine for several months or 6-10,000 miles, because they have been used to changing the crude based oils every 3-4,000 miles but it is perfectly viable (and cost effective). In any case, compared with the cost of an engine rebuild, synthetic oil is the bargain of the century.


BTW, forget the additives - they are not necessary with synthetics at all.


Dave M

'78 F150 Super Cab 4X4 (351M)
'72 Gran Torino Sport SportsRoof (351C)
'65 Falcon Futura convert (289)

 

K...with all that said, I hear a lot about the PPM Zinc levels in oil, but what I don't know is what exactly is Zinc and how does it protect the camshaft I hear about so often?

OJ