Older vehicles, switch from Dino to Synth?

[tomrscott]

Here is a slightly different question than I've seen before.

I have several vehicles with high miles that have gotten this far on "good quality" dino oil, mostly Castrol 10W40.

'91 Landcruiser 241k miles
'98 Subaru 150k miles
'88 Nissan Pathfinder 163k miles

And we just added:
'00 JD 790 1319 hours

They all run well enough to be essentially indistinguishable from new. The Landcruiser leaks a bit at the main seals, but I just figure that is more reason to keep up with regular oil changes. The other three are all bone dry underneath. We normally change in 3k to 5k intervals. A few times, life has gotten "complicated" and I have gone 10k or so on the Landcruiser.

Now that we've just gotten the JD, I have been trying to learn more about oils and fuels and things and am starting to think seriously about using synth oil.

My questions are:
1) If I start using something like the Rotella synthetic, for the JD, should I just get it in quantity and use it in all these vehicles? With an older vehicle that has been "well broken-in" on dino oil (whether that was a good thing or not), is there much to gain from switching to synthetic late in the engine's life? (Well, the Landcruiser is still just a baby! /forums/images/graemlins/wink.gif)

2) Will the Synthetic leak about the same from LC's seals, or worse, or less than the 10W40 Castrol I've been using?

3) Would you use a good synth in the JD, and then blend that with Rotella dino for the gas vehicles?

I don't want to start another oil war, but I am curious about these issues and haven't seen them discussed.

Thanks!

Planning to check out prices at Walmart tomorrow. /forums/images/graemlins/ooo.gif

 

[BobCorazza]

I switched my wife's van over to full synthetic at 100k and our 'beater" car at 145k with no issues. Personnaly, I would not hesitate to switch to synthetic in most any application.

As far as one oil for your fleet, that would depend upon mfg specs and the climate. Seeing as you have been using a 40 weight without trouble, a 15w40 for all should be OK in temps (IMHO) of greater than 20 deg. F, though most mfgs use 0-10 deg f as the lower limit for a 15w.

 

[cp1969]

I only have one data point to share with you.

I had heard the old wives tale about synthetic oil causing oil leaks in older engines, but it went in one ear and out the other.

Honda motorcycles are not known for leaking oil. If anything, the opposite is true. I bought an old Magna with 35k on the clock, but it was clean and did not leak a drop. Soon after buying it, of course I had to come to the internet to learn all about it and found that the cam oiling on these models was pretty poor and synthetic oil was a must.

To sum it up, after switching to Mobil 1 15w-50, it started leaking oil as bad or worse than any old Harley or Triumph I've ever owned.

Coincidence? Maybe. But maybe there was something to the old wives tale about synthetic causing leaks.

 

[JimR]

I have heard that switching over to synthetic is not good on high mileage motors. Why? I heard that it may clean out any varnish and buildup inside your motor which can cause leaks and oil usage. I guess someone that has done it may be able to shed more light on the subject. I personally would not do it with those kind of high mileage vehicles.

 

[sneaky_pete]

All my vehicles run Mobil 1 in their crankcases; it's better than any conventional oil and it's available anywhere.

I also have a '91 Land Cruiser; I bought it second-hand at about 100,000 miles and immediately switched to Mobil-1. It also has a leaky rear main seal, but it didn't get any worse when I switched to synthetic. One of these days when I have some time I guess I'll have to pull the tranny, exhaust, etc. and replace the seal, but meanwhile it doesn't bother me much.

As long as your climate (temperature range) is compatible with the grade of Rotella you choose, there is nothing wrong with running it in all your crankcases. Oil rated for diesel service has better additives than oil rated for gasoline only.

 

[dmp437]

Mobil 1 in all my vehicles also. Comes from Sam's Club unless it's on sale at WalMart or Meijer's (Midwest chain similiar to WalMart).
The synthetic's properties would be an added benefit to older vehicles, especially in colder weather.

 

[RalphVa]

I've switched to Mobil 1 in every engine now. Started with air cooled ones. All 3 vehicles were switched this summer. None of them had any seal leakages leaving puddles: VW Cabrio @ 70k, Toyota Tacoma @ 129k, Benz 240D @ 188k. Only oil added so far was about half a quart to the Benz. It has always used a 1/2 quart to a quart in 2k miles all its days. Think its tad of seal leakage that caused wetting of the pan a tad has stopped: no more diesel turds on the floor (not really puddles, just sorta like oil blob turds; they're gone).

Switched the Gravely at about 150 hours. Now has about 350 hours. Still uses some oil like it always did.

New, different oil could cause seals to stop. That's my clue for replacing power steering and transmission (manual) oil, when the seals start slinging. New oil usually seals them all up. Even oil change on the Gravely transmission mostly sealed up the right axle seal leak.

Oh, I switched out the power steering fluid on the Tacoma and Cabrio to synthetic. One line on the Tacoma that had no clamp on it slipped off. Put a clamp on and refilled. No problems since.

ExxonMobil say you'll get a 4% fuel mileage increase and about that in power increase (racing experience on the power increase). I was estimating 3% fuel mileage increase from my mileage records so far. This will just about pay for the cost increase, particularly if you double the change interval.

Ralph

Ralph

 

[RalphVa]

By the way, Castrol doesn't make a drop of oil. They were buying almost entirely from Exxon before I retired. They had their own ad-pack. They'd just buy the base oil and blend it up and can it.

Ralph

 

[gsxr1100]

If you switch to Mobil 1, Mobil recommends you do not extended drains. So take that for what it is worth.

 

[fractal]

I run delo-400 15w40 in a 91 dodge caravan with 150k, a 91 ford f350 diesel with 250k and kubota b7200. I just switched the caravan last oil change and have not seen any issues. My wife let oil changers sell her "high milage oils" the last few times she had them change the oil and it was always down a quart or so at 3k. Am now at 2k on this oil change and have seen no oil consumption with the delo.

I picked delo 400 because costco sells it by the case and I can put it in every vehicle I own other than the sedan. It wants 5w20 to meet california emissions, 10w30 anywhere but here.

I could save a few dollars by buying separate oils for the gaser than the diesels but that would mean keeping more oil on the shelf. The f350 uses 10 qts of oil every change and the caravan only 5. The delo hdeo runs me 1.50 a quart whereas regular motor oil goes for under a buck a quart. It is worth the extra 2.50 an oil change to me to not have to keep track of two different oils. That and I choose to believe that the HDEO is better than the regular motor oil in my car /forums/images/graemlins/wink.gif