Whats the difference in oils?

Submitted: Wednesday, Jan 28, 2004 at 00:25
ThreadID: 10069 Views:1720 Replies:7 FollowUps:4
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Hi all,

Please can anyone explain to me in laymans terms the difference between mineral oil and synthetic oil and the advantages and disadvantages of both.

I have a 2003 TD Bravo and am using Caltex CXJ 15W - 40 oil at present which is a mineral oil but am thinking of changing to Caltex Delo 400 which is a synthetic oil. The oil is changed every 5,000km. Any comments greatly appreciated.

Regards

Les
Have beast - will travel!
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Reply By: David N. - Wednesday, Jan 28, 2004 at 09:51

Wednesday, Jan 28, 2004 at 09:51
There is only ONE disadvantage with synthetic oils...... cost.
They are superior in every other respect.

The cost is unfortunately a huge consideration with a diesel as the oil change intervals can not be extended too much, due to soot build up in the oil, although this can be reduced somewhat by very good filtration such as bypass filtering.
IMHO for a petrol engine there is no arguement for staying with mineral oils, as the cost is more than compensated for by extended change intervals and much better engine protection both hot and cold.
AnswerID: 44592

Reply By: David O - Wednesday, Jan 28, 2004 at 10:03

Wednesday, Jan 28, 2004 at 10:03
Does this ue for older petrol engines? I have a 1990 Rangie with 150K on the clock, I've been reluctant to change to synthetic becasue I was told it was not suitable for older engines.
AnswerID: 44593

Follow Up By: David N. - Wednesday, Jan 28, 2004 at 10:58

Wednesday, Jan 28, 2004 at 10:58
I have heard that occasionally from people in the past.... and asked them to explain why that would be so. Nobody has EVER explained successfully how to back up that arguement.
IMHO, how can an oil which is better in every respect, be bad for older engines, assuming one DOES get the correct viscosity.......? Perhaps if your engine was full of sludge and dirt it might block the filter quickly, but you can always do your first oil filter change early after going synthetic if that's a concern.
If possible, cut your filter open and see what's in it when you change the filter- very easy with a paper cartridge but a lot more difficult with the spin-on variety. (On aircraft engines it is mandatory to look at the oil filter every time it's changed.)

Now I even run my 20 yr old Briggs and Stratton mower on Mobil 1 or the equivalent Shell synthetic! (Depends on what I have in the garage at the time...)
Cheers
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Follow Up By: Stuart - Thursday, Jan 29, 2004 at 20:12

Thursday, Jan 29, 2004 at 20:12
I beg to differ. I had an old holden 308 rebuilt by a GOOD engine shop and was told specificly NOT to use the modern oils including synthetics because he had seen cases of the rubber oil seals and valve stem seals break down because of the addatives used. Also you need to watch the viscosity levels as a lot of the synthetics are thinner and in an old engine you can have oil preasure problems. Another thing I have been told many times is what ever brand of oil you use, stick with it or do a proper engine flush because different manufactures use different formulas in the base oil and the're not always compatable.
Just my two bobs worth...
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Reply By: Big Trev - Wednesday, Jan 28, 2004 at 14:49

Wednesday, Jan 28, 2004 at 14:49
Not that this is terribly relevant, but I thought I would pass it on anyway. When I purchased the old MQ Nissan back in '89 I was unsure of its last oil change so I did the right thing and did the oil change, I used a hight grade mineral oil, and as David indicated above this engine was full of sludge etc, well the downshot of all this was that the superior oil flushed the engine clean and the goddam thing started using oil which it hadn't done until I changed the goddam oil.

AnswerID: 44624

Reply By: basecamp15 - Wednesday, Jan 28, 2004 at 15:06

Wednesday, Jan 28, 2004 at 15:06
I know your using Caltex but this site was where I went in order to answer the same question. I just waiting on cost difference to see if it's worth it as I have a Patrol TD42T and these engines are very reliable so probably don't need the synthetic stuff.
Cheers, Mark.
AnswerID: 44627

Reply By: Rick Blaine - Wednesday, Jan 28, 2004 at 17:02

Wednesday, Jan 28, 2004 at 17:02
Hi Les,
I have a T/D Jackeroo. After some long and at times acrimonious discussions with Holden I am now using Castrol soft tec. Its synthetic but allows a 10000km change and costs $158 /20 litres. Because the Jack needs a 5 weight oil I cant find a mineral oil that will do the job so a top shelf oil is needed. I'm obviously out of touch because I thought that a turbo would need the extra protection that synthetic gives. Not all synthetics are suited to diesels however just make sure that if you do change you use a diesel formulated synthetic and ask if you can extend your change interval which would be to both your financial & practical advantage other wise stick to the mineral.
AnswerID: 44640

Reply By: hoyks - Wednesday, Jan 28, 2004 at 18:37

Wednesday, Jan 28, 2004 at 18:37
I use DELO 400. I only pay around $80 to $90 for 20L, so the price isn't that bad when compared to buying a 4 x 5L at an auto parts store.
AnswerID: 44650

Follow Up By: hoyks - Wednesday, Jan 28, 2004 at 18:39

Wednesday, Jan 28, 2004 at 18:39
that 4 x 5L of a mineral oil. I knew what I meant
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Reply By: David O - Wednesday, Jan 28, 2004 at 21:10

Wednesday, Jan 28, 2004 at 21:10
Well, that does it then, the Rangie is going synthetic at the next oil change.

David O
AnswerID: 44663

Follow Up By: David O - Wednesday, Jan 28, 2004 at 21:35

Wednesday, Jan 28, 2004 at 21:35
Any other Rangie owners out there?
Check this....

http://www.britishpacific.com/rr/FAQ_synthetics.html

basically says superior but at a cost which seems to be the concencus here.
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