Synthetic Oil Change Schedule

RoyLuke

Well-known member
Apr 18, 2007
150
2
1996 LR Discovery
4.0 Litre

HI all;
I converted over to Synthetic oil when I overhauled the engine a few years back.
The Service Manual recommends to change the oil and filter every 6000 miles or every 6 months. This is based on fossil oil.
Synthetic lasts a good bit longer but what is the "normal" Synthetic oil change schedule?

TNX
Roy
 

seventyfive

Well-known member
Jan 3, 2010
4,278
99
over there
You should have ran 30 weight non detergent the first 1000 miles, then change oil.
as far as service intervals stick to 5,000 even with synthetic. The fuel trim is rich and you get dirty oil in those engines.
Most people here say run 15w40 dyno but time each their own.
you should also add zinc.
the old rotella 15w40 removed almost all the sulphur and zinc so they could sell it at Walmart and other chains.
 

Tugela

Well-known member
May 21, 2007
4,377
201
Seattle
Along with "what tires should I get?" and "what suspension lift should I get?" this is one of the most frequently asked questions on this site. Which also means there is a wealth of existing discussion on the topic, so I suggest starting with a search of this forum.

I don't understand why people continue to insist on putting synthetic oil in 25+ year old trucks that are running on 1970s engine technology. Maybe I'm missing something. I asked 5 different indie Rover mechanics with a collective 100+ years of experience this question and they all recommended high-zinc conventional oil changed at 3,000 mile intervals. The tech I trust the most recommends 20W50, so I've been using that weight in my engine for years. Mind you, this spec oil may be appropriate to the temperate climate of the Pacific Northwest and something else may work better for winters in North Dakota or year round in Miami.
 

gimebakmybulits

Well-known member
Dec 11, 2013
1,056
74
Pasadena
Anecdotal and just my situation (I don't drive the Disco that often) but I get less knock in the first 30-60 seconds of startup and better cold starts with synthetic 5w-40 (Rotella T6) than with the Rotella 15w-40.
 

pdogg

Well-known member
Jul 18, 2005
1,198
21
Phoenix, AZ
which synthetic oil did you convert to and did you check to see if it's well rated for flat tappet engines? The word "synthetic" does not mean its "good" for our LR v8s..
 
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seventyfive

Well-known member
Jan 3, 2010
4,278
99
over there
That’s why you add zinc every oil change.
like I posted, be careful of rotella, brad penn, etc. they had to remove zinc and sulphur so they could sell it at box stores.
personally I always used redline 10w40 with zinc additive. At the end of the day use whatever you want just collect the data we provide.
typically these threads inevitably turn into a political news briefing...everyone is a certified oil analysis expert and if you don’t agree with me you’re a fucking idiot!
 
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luckyjoe

Well-known member
Oct 10, 2004
316
33
New Jersey USA
Mobil1 0W40 - 1000ppm Phosphorus / 1100ppm Zinc
Mobil1 Turbo Diesel Truck 5W40 - 1100ppm Phosphorus / 1300ppm Zinc (meets CI-4, CI-4 Plus)

Another good one is Mobil Delvac 1 5w40, but I don't have the specs (should be similar to M1-TDT 5W40 above)
 

pdogg

Well-known member
Jul 18, 2005
1,198
21
Phoenix, AZ
Many people chose to go Diesel grade oil to reach the HTHS rating of their oil without worrying about Zinc.. I have been using Chevron Delo 400 15/40 for the longest time... but I also live in a southern climate. Many people also go with Rotella and similar.. if I recall the HTHS rating or your oil should be 3.5 or higher. most newer engine oils now can't meet that.. without adding zinc, or moving to a diesel grade oil..
 

patdohere

Active member
Sep 30, 2020
34
5
San Diego, CA
Along with "what tires should I get?" and "what suspension lift should I get?" this is one of the most frequently asked questions on this site. Which also means there is a wealth of existing discussion on the topic, so I suggest starting with a search of this forum.

I don't understand why people continue to insist on putting synthetic oil in 25+ year old trucks that are running on 1970s engine technology. Maybe I'm missing something. I asked 5 different indie Rover mechanics with a collective 100+ years of experience this question and they all recommended high-zinc conventional oil changed at 3,000 mile intervals. The tech I trust the most recommends 20W50, so I've been using that weight in my engine for years. Mind you, this spec oil may be appropriate to the temperate climate of the Pacific Northwest and something else may work better for winters in North Dakota or year round in Miami.
I’m about to do a oil change on a 1996 Disco with 201k miles. Where do you get your oil?